Articulating implant connectors and related methods

ABSTRACT

Articulating implant connectors and related methods are disclosed herein. Exemplary connectors can include first and second bodies that are rotatable relative to one another about a rotation axis and selectively lockable to resist or prevent such rotation. Each of the bodies can be configured to couple to a rod or other fixation component, and the connector can be used to lock first and second rods together even when the rods are obliquely angled with respect to one another.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/926,051, filed on Mar. 20, 2018. U.S. patent application Ser. No.15/926,051 is a continuation-in-part of U.S. patent application Ser. No.15/471,075, filed on Mar. 28, 2017, and now issued as U.S. Pat. No.10,561,454. The entire contents of each of these applications areincorporated herein by reference.

FIELD

Articulating implant connectors and related methods are disclosedherein.

BACKGROUND

Fixation systems can be used in orthopedic surgery to maintain a desiredspatial relationship between multiple bones or bone fragments. Forexample, various conditions of the spine, such as fractures,deformities, and degenerative disorders, can be treated by attaching aspinal fixation system to one or more vertebrae. Such systems typicallyinclude a spinal fixation element, such as a rigid or flexible rod orplate, that is coupled to the vertebrae by attaching the element tovarious anchoring devices, such as screws, hooks, or wires. Onceinstalled, the fixation system holds the vertebrae in a desired positionuntil healing or spinal fusion can occur, or for some other period oftime.

There are many instances in which it may be desirable to connectmultiple implants to each other. For example, some revision surgeriesinvolve extending a previously-installed construct to additionalvertebral levels by coupling a newly-installed spinal rod to apreviously-installed rod. By way of further example, aspects of thepatient's anatomy, the surgical technique used, or the desiredcorrection may require that multiple spinal rods be connected to oneanother. As yet another example, coupling multiple rods to one anothercan improve the overall strength and stability of an implantedconstruct.

There can be various difficulties associated with connecting multipleimplants to each other. The available space for the implanted constructcan often be very limited, particularly in the cervical area of thespine. Also, aligning and positioning implants and connectors in thesurgical wound may be challenging or cumbersome for the surgeon. Thereis a continual need for improved implant connectors and related methods.

SUMMARY

Articulating implant connectors and related methods are disclosedherein. Exemplary connectors can include first and second bodies thatare rotatable relative to one another about a rotation axis andselectively lockable to resist or prevent such rotation. Each of thebodies can be configured to couple to a rod or other fixation component,and the connector can be used to lock first and second rods togethereven when the rods are obliquely angled with respect to one another.

In some embodiments, a connector can include a first body that defines afirst rod-receiving recess, the first body having proximal and distalends that define a proximal-distal axis extending therebetween; a secondbody that defines a second rod-receiving recess, the second body havingproximal and distal ends that define a proximal-distal axis extendingtherebetween; a hinge pin that couples the first body to the secondbody, a central longitudinal axis of the hinge pin defining a rotationaxis about which the first and second bodies rotate relative to oneanother; and a fastener movable with respect to at least one of thefirst and second bodies to urge the first and second bodies towards oneanother along the rotation axis and thereby lock relative rotation ofthe first and second bodies about the rotation axis.

The fastener can secure a rod to one of the first and secondrod-receiving recesses. The fastener can be a first fastener configuredto secure a first rod within the first rod-receiving recess. Theconnector can include a second fastener configured to secure a secondrod in the second rod-receiving recess. The hinge pin can be formedintegrally with the first body. The hinge pin can be rotatable relativeto both of the first and second bodies. The first and second bodies caninclude respective bearing surfaces configured to bear against oneanother to lock relative rotation of the first and second bodies aboutthe rotation axis. The bearing surfaces can be defined by complementarymale and female structures of the first and second bodies. The firstbody can include a conical male projection, an outer surface of whichdefines the bearing surface of the first body. The second body caninclude a conical female recess, an inner surface of which defines thebearing surface of the second body. The bearing surfaces can eachinclude teeth or splines. The hinge pin can be received within a cavityformed in the first body or the second body. The hinge pin can translatelongitudinally within the cavity as the fastener is moved relative tosaid at least one of the first and second bodies. The proximal-distalaxes of the first and second bodies can be obliquely angled with respectto one another. A force applied by the fastener can be transferred tothe hinge pin through a saddle. The saddle can include a conical surfacethat engages and bears against a corresponding conical surface of thehinge pin to pull the first and second bodies towards one another. Thesaddle can include a keel extending distally therefrom. The keel can bereceived within a slot formed in the hinge pin. The keel can have abearing surface that engages and bears against a corresponding bearingsurface of the slot to pull the first and second bodies towards oneanother. The bearing surfaces of the keel and the slot can lie in planesthat are obliquely angled with respect to the rotation axis. The saddlecan include first and second keels defining a space therebetween inwhich a central rib of the hinge pin is received. The first and secondkeels can have bearing surfaces that engage and bear againstcorresponding bearing surface of the hinge pin. The hinge pin caninclude a rod seat formed therein. The rod seat can be configured suchthat urging a rod against the rod seat causes the hinge pin to translaterelative to at least one of the first and second bodies along therotation axis. The rod seat can be positioned relative to the firstrod-receiving recess such that a lateral sidewall of the rod seatinterferes with a rod as the rod is seated in the first rod-receivingrecess. The rod seat can be curved in multiple planes.

In some embodiments, a connector can include a first body that defines afirst rod-receiving recess; a hinge pin formed integrally with the firstbody and extending laterally therefrom to a free end; a second body thatdefines a second rod-receiving recess, the second body having a cavityin which the free end of the hinge pin is received to couple the secondbody to the first body such that the first and second bodies rotaterelative to one another about a rotation axis; a first fastenerconfigured to secure a first rod within the first rod-receiving recess;and a second fastener configured to secure a second rod within thesecond rod-receiving recess and to urge the first and second bodiestowards one another along the rotation axis to lock relative rotation ofthe first and second bodies about the rotation axis.

The second fastener can be configured to bear against a saddle disposedwithin the second rod-receiving recess to urge a bearing surface of thesaddle against a bearing surface of the hinge pin to move the first andsecond bodies towards one another. The second fastener can be configuredto bear against a rod disposed within the second rod-receiving recess tourge the rod against a rod seat of the hinge pin to move the first andsecond bodies towards one another.

In some embodiments, a surgical method can include inserting a first rodinto a first rod-receiving recess of a first body of a connector;inserting a second rod into a second rod-receiving recess of a secondbody of the connector, the second body being coupled to the first bodyby a hinge pin; rotating the first body relative to the second bodyabout a rotation axis defined by the hinge pin; moving a fastener withrespect to at least one of the first and second bodies to urge the firstand second bodies towards one another along the rotation axis andthereby lock relative rotation of the first and second bodies about therotation axis; and securing the first and second rods to an anatomy of apatient.

The first rod can be secured to a cervical spine of the patient by oneor more bone anchors and the second rod can be secured to a thoracicspine of the patient by one or more bone anchors. Rotating the firstbody relative to the second body can cause the first and second rods tobe obliquely angled with respect to one another. Moving the fastener canbe effective both to secure one of the first and second rods to theconnector and to lock rotation of the connector.

In some embodiments, a connector can include a first body that defines afirst rod-receiving recess; a hinge pin extending laterally from thefirst body to a free end; a second body that defines a secondrod-receiving recess, the second body having a cavity in which the freeend of the hinge pin can be received to couple the second body to thefirst body such that the first and second bodies rotate relative to oneanother about a rotation axis of the hinge pin; a first fastenerconfigured to secure a first rod within the first rod-receiving recess;and a second fastener configured to secure a second rod within thesecond rod-receiving recess. The hinge pin can have planar surfaces thatintersect to form one or more corners. The corners of the hinge pin canapply a force against the cavity of the second body that locks the hingepin in place when the second fastener secures the second rod within thesecond rod-receiving recess.

A cross section of the hinge pin can have a polygonal profile. Theconnector can further include a saddle disposed within the secondrod-receiving recess. The saddle can include a saddle protrusionextending distally therefrom. The saddle protrusion can be receivedwithin a slot formed in the hinge pin. The force applied by one or morecorners of the hinge pin can be transferred from a force applied by thesecond fastener through the saddle. The saddle protrusion can limit arotation of the hinge pin within the cavity of the second body when aterminal end of the slot of the hinge pin engages and bears against thesaddle protrusion. The saddle can have a bearing surface adjacent to thesaddle protrusion that engages and bears against a corresponding bearingsurface of the hinge pin adjacent to the slot. The slot of the hinge pincan be formed radially about a central rib of the hinge pin. The saddleprotrusion of the saddle can define a depression in which the centralrib of the hinge pin is received.

In some embodiments, the connector can include a first body that definesa first rod-receiving recess; a hinge pin extending laterally from thefirst body to a free end; a second body that defines a secondrod-receiving recess, the second body having a cavity in which the freeend of the hinge pin can be received to couple the second body to thefirst body such that the first and second bodies rotate relative to oneanother about a rotation axis of the hinge pin; a saddle defining a rodseat disposed within the second rod-receiving recess, the saddleincluding a saddle protrusion extending distally therefrom, the saddleprotrusion being received within a slot formed in the hinge pin; a firstfastener configured to secure a first rod within the first rod-receivingrecess; and a second fastener configured to secure a second rod on therod seat of the saddle. The slot of the hinge pin can have an angled camsurface that can engage and bear against a corresponding angled bearingsurface of the saddle protrusion to lock the hinge pin in place when thesecond fastener secures the second rod within the second rod-receivingrecess.

The angled cam surface of the slot can be oriented at an oblique anglewith respect to the longitudinal axis of the hinge pin. The angledbearing surface of the saddle protrusion can be oriented at an obliqueangle with respect to the longitudinal axis of the hinge pin. The angledbearing surface of the saddle protrusion can be oriented to match theoblique angle of the angled cam surface of the slot in the hinge pin.The saddle protrusion can have a wedge-shaped cross section that canapply a force against the angled cam surface of the slot of the hingepin to lock the hinge pin in place when the second fastener secures thesecond rod within the second rod-receiving recess.

In some embodiments, the connector can include a first body that definesa first rod-receiving recess; a hinge pin extending laterally from thefirst body to a free end; a second body that defines a secondrod-receiving recess, the second body having a cavity in which the freeend of the hinge pin can be received to couple the second body to thefirst body such that the first and second bodies rotate relative to oneanother about a rotation axis of the hinge pin; a first fastenerconfigured to secure a first rod within the first rod-receiving recess;and a second fastener configured to secure a second rod within thesecond rod-receiving recess. The free end of the hinge pin can extendthrough the cavity and into an opening defined in the second body. Theopening can have a cross sectional shape that limits rotation of thefree end of the hinge pin relative to the second body about the rotationaxis.

The free end of the hinge pin can have a cross sectional shapeconfigured to rotate within the opening of the second body. The crosssectional shape of the free end of the hinge pin and the cross sectionalshape of the opening can define a degree of rotation of the free end ofthe hinge pin. The cross sectional shape of the opening of the secondbody and the cross sectional shape of the free end of the hinge pin canbe D-shaped. The D-shaped cross section of the opening of the secondbody can have an area greater than an area of the D-shaped cross sectionof the free end of the hinge pin.

The second fastener can be configured to bear against a saddle disposedwithin the second rod-receiving recess to urge a bearing surface of thesaddle against a corresponding bearing surface of the hinge pin. Thesaddle can include a saddle protrusion extending distally from an edgeof the saddle adjacent to the bearing surface of the saddle. The saddleprotrusion can be received within a slot formed in the hinge pinadjacent to the bearing surface of the hinge pin. The slot of the hingepin can be aligned with an edge of the second rod-receiving recess whenthe free end of the hinge pin is inserted into the through hole openingof the second body. The bearing surface of the hinge pin can bearagainst the bearing surface of the saddle for a continuous length thatis greater than half the width of the second rod-receiving recess.

In some embodiments, the connector can include a first body that definesa first rod-receiving recess; a hinge pin extending laterally from thefirst body to a free end; a second body that defines a secondrod-receiving recess, the second body having a cavity in which the freeend of the hinge pin can be received to couple the second body to thefirst body such that the first and second bodies rotate relative to oneanother about a rotation axis of the hinge pin; a saddle defining a rodseat disposed within the second rod-receiving recess, the saddleincluding a saddle protrusion extending distally therefrom, the saddleprotrusion being received within a slot formed in the hinge pin; a firstfastener configured to secure a first rod within the first rod-receivingrecess; and a second fastener configured to secure a second rod on therod seat of the saddle. The slot of the hinge pin can be aligned with anedge of the second rod-receiving recess when the free end of the hingepin is inserted into the cavity of the second body.

The saddle protrusion can extend distally from an edge of the saddleadjacent to a bearing surface of the saddle. The saddle protrusion canbe received within the slot of the hinge pin. The bearing surface of thesaddle can bear against a bearing surface of the hinge pin for acontinuous length that can be greater than half the width of the secondrod-receiving recess.

In some embodiments, a surgical method can include inserting a first rodinto a first rod-receiving recess of a first body of a connector, thefirst body including a hinge pin that extends laterally therefrom to afree end; inserting a second rod onto a rod seat formed in a saddledisposed in a second rod-receiving recess of a second body of theconnector, the hinge pin of the first body being inserted into a cavityformed in the second body and thereby coupling the first body of theconnector to the second body of the connector; rotating the first bodyrelative to the second body about a rotation axis defined by the hingepin, such that a slot formed in the hinge pin rotates about a saddleprotrusion extending distally from the saddle; moving a fastener withrespect to the second body to secure the second rod within the secondrod-receiving recess and thereby lock relative rotation of the first andsecond bodies about the rotation axis; and securing the first and secondrods to an anatomy of a patient.

Moving the fastener with respect to the second body can urge a bearingsurface of the saddle against a corresponding bearing surface of thehinge pin and thereby cause one or more corners of the hinge pin toapply a force against the cavity of the second body. Rotating the firstbody relative to the second body about a rotation axis defined by thehinge pin can include rotating the first body with respect to the secondbody such that the saddle protrusion can limit a rotation of the hingepin when a terminal end of the slot of the hinge pin engages and bearagainst the saddle protrusion. The slot of the hinge pin can have anangled cam surface and the saddle protrusion can have a correspondingangled bearing surface. Moving the fastener with respect to the secondbody can wedge the angled bearing surface of the saddle protrusion intothe angled cam surface of the slot. Rotating the first body relative tothe second body about a rotation axis defined by the hinge pin caninclude rotating the first body such that the free end of the hinge pinrotates within an opening defined in the second body of the connector.The opening can have a cross sectional shape that limits rotation of thefree end of the hinge pin. Rotating the first body relative to thesecond body about a rotation axis defined by the hinge pin can includerotating the first body such that the slot of the hinge pin rotatesabout the saddle protrusion that extends distally from an edge of thesaddle and can be aligned with an edge of the second rod-receivingrecess. Moving the fastener with respect to the second body can urge abearing surface of the saddle against a corresponding bearing surface ofthe hinge pin for a continuous length that is greater than half thewidth of the second rod-receiving recess.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a connector, shown with first andsecond rods;

FIG. 1B is an exploded perspective view of the connector of FIG. 1A;

FIG. 1C is a sectional side view of the connector and rods of FIG. 1A;

FIG. 1D is a partial exploded view of the connector of FIG. 1A;

FIG. 1E is a perspective view of a first body of the connector of FIG.1A;

FIG. 1F is another perspective view of the first body of FIG. 1E;

FIG. 1G is a perspective view of a first saddle of the connector of FIG.1A;

FIG. 1H is another perspective view of the first saddle of FIG. 1G;

FIG. 1I is a perspective view of a hinge pin of the connector of FIG.1A;

FIG. 1J is an end view of the hinge pin of FIG. 1I;

FIG. 1K is a side view of the hinge pin of FIG. 1I;

FIG. 1L is a top view of the hinge pin of FIG. 1I;

FIG. 2A is a perspective view of a connector, shown with first andsecond rods;

FIG. 2B is an exploded perspective view of the connector of FIG. 2A;

FIG. 2C is a sectional side view of the connector and rods of FIG. 2A;

FIG. 2D is a perspective view of a second body of the connector of FIG.2A;

FIG. 2E is another perspective view of the second body of FIG. 2A;

FIG. 3A is a perspective view of a connector, shown with first andsecond rods;

FIG. 3B is an exploded perspective view of the connector of FIG. 3A;

FIG. 3C is a sectional side view of the connector and rods of FIG. 3A;

FIG. 3D is a perspective view of a saddle of the connector of FIG. 3A;

FIG. 3E is a side view of the saddle of FIG. 3D;

FIG. 3F is another perspective view of the saddle of FIG. 3D;

FIG. 3G is a perspective view of a first body of the connector of FIG.3A;

FIG. 3H is a perspective view of a second body of the connector of FIG.3A;

FIG. 3I is a top view of an alternate first body of the connector ofFIG. 3A;

FIG. 3J is an end view of an alternate saddle of the connector of FIG.3A

FIG. 3K is a side view of the alternate first body of FIG. 3I;

FIG. 3L is a side view of the alternate saddle of FIG. 3J;

FIG. 4A is a perspective view of a connector, shown with first andsecond rods and with first and second fasteners of the connectoromitted;

FIG. 4B is an exploded perspective view of the connector of FIG. 4A;

FIG. 4C is a sectional side view of the connector of FIG. 4A;

FIG. 4D is a perspective view of a second body of the connector of FIG.4A;

FIG. 4E is a side view of a first body of the connector of FIG. 4A;

FIG. 4F is a perspective sectional view of the first body of theconnector of FIG. 4A;

FIG. 5A is a perspective view of a connector, shown with first andsecond spinal rods;

FIG. 5B is an exploded perspective view of the connector of FIG. 5A;

FIG. 5C is a perspective view of a first body of the connector of FIG.5A;

FIG. 5D is another perspective view of the first body of FIG. 5C;

FIG. 5E is an end view of the first body of FIG. 5C;

FIG. 5F is a top view of the connector of FIG. 5A, shown with the saddleof the connector omitted;

FIG. 5G is a perspective view of a second body of the connector of FIG.5A;

FIG. 5H is another perspective view of the second body of FIG. 5G;

FIG. 5I is a perspective view of the saddle of the connector of FIG. 5A;

FIG. 5J is a sectional side view of the connector of FIG. 5A, shown withthe fasteners of the connector omitted;

FIG. 5K is another perspective view of the saddle of FIG. 5I;

FIG. 5L is an end view of the saddle of FIG. 5I;

FIG. 5M is another perspective view of a connector, shown with thesecond body as transparent;

FIG. 5N is a sectional end view of the connector of FIG. 5A, shown withthe fasteners of the connector omitted;

FIG. 5O is another sectional end view of the connector of FIG. 5A, shownwith the fasteners of the connector omitted;

FIG. 6A is a perspective view of a connector, shown with the fastenersof the connector omitted;

FIG. 6B is an exploded perspective view of the connector of FIG. 6A;

FIG. 6C is a perspective view of a first body of the connector of FIG.6A;

FIG. 6D is top view of the connector of FIG. 6A, shown with the saddleof the connector omitted;

FIG. 6E is a perspective view of the saddle of the connector of FIG. 6A;

FIG. 6F is another perspective view of the saddle of FIG. 6E;

FIG. 6G is another perspective view of the saddle of FIG. 6E;

FIG. 6H is another perspective view of the connector of FIG. 6A, shownwith the second body of the connector as transparent;

FIG. 6I is a sectional side view of the connector of FIG. 6A, shown withthe fasteners omitted;

FIG. 6J is bottom view of the connector of FIG. 6A, shown with thesecond body of the connector as transparent;

FIG. 7A is a perspective view of a connector, shown without thefasteners of the connector;

FIG. 7B is an exploded perspective view of the connector of FIG. 7A;

FIG. 7C is a side view of a first body of the connector of FIG. 7A;

FIG. 7D is a top view of the first body of FIG. 7C;

FIG. 7E is an end view of the first body of FIG. 7C;

FIG. 7F is a side view of a second body of the connector of FIG. 7A;

FIG. 7G is a perspective view of the second body of FIG. 7F;

FIG. 7H is another perspective view of the second body of FIG. 7F;

FIG. 7I is a side view of the saddle of the connector of FIG. 7A;

FIG. 7J is a perspective view of the saddle of FIG. 7I;

FIG. 7K is another perspective view of the saddle of FIG. 7I;

FIG. 7L is another perspective view of the connector of FIG. 7A, shownwith the saddle and the fasteners of the connector omitted;

FIG. 7M is a sectional side view of the connector of FIG. 7A;

FIG. 7N is an end view of the connector of FIG. 7A;

FIG. 7O is a sectional end view of the connector of FIG. 7A, shown withthe fasteners of the connector omitted; and

FIG. 8 is a perspective view of a human spine with a fixation systemattached thereto.

DETAILED DESCRIPTION

Articulating implant connectors and related methods are disclosedherein. Exemplary connectors can include first and second bodies thatare rotatable relative to one another about a rotation axis andselectively lockable to resist or prevent such rotation. Each of thebodies can be configured to couple to a rod or other fixation component,and the connector can be used to lock first and second rods togethereven when the rods are obliquely angled with respect to one another.

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the devices andmethods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments.

FIGS. 1A-1L illustrate an exemplary embodiment of a connector 100. Asshown, the connector 100 can include a first body 102 that defines afirst rod-receiving recess or channel 104 and a second body 106 thatdefines a second rod-receiving recess or channel 108. The first andsecond bodies 102, 106 can be connected to one another at least in partby a hinge pin 110. The hinge pin 110 can define a rotation axis A1about which the first and second bodies 102, 106 can rotate relative toone another. The connector 100 can include first and second fasteners112, 114 configured to secure respective first and second rods R1, R2 orother fixation elements to the connector 100.

At least one of the fasteners 112, 114 can further be configured to urgethe first and second bodies 102, 106 towards one another and therebylock relative rotation of the first and second bodies about the rotationaxis A1. For example, the first fastener 112 can be tightened to securea first rod R1 within the first body 102 and to apply a force to a firstramped, curved, or otherwise tapered surface 116 of the hinge pin 110 todraw the first and second bodies 102, 106 towards one another, lockingrotation therebetween. In the illustrated embodiment, a force applied bythe first fastener 112 is transferred to the hinge pin 110 through thefirst rod R1 and through a first saddle 118 disposed between the firstrod and the hinge pin. In other arrangements, the saddle 118 can beomitted and the first rod R1 can bear directly against the hinge pin110. In still further arrangements, the first fastener 112 can beardirectly against the saddle 118. For example, the first fastener 112 caninclude an outer set screw that bears against the saddle 118 to lockrelative rotation of the bodies 102, 106, and an inner set screw thatbears against the first rod R1 to secure the first rod to the connector100.

Similarly, the second fastener 114 can be tightened to secure a secondrod R2 within the second body 106 and to apply a force to a secondramped, curved, or otherwise tapered surface 120 of the hinge pin 110 todraw the first and second bodies 102, 106 towards one another, lockingrotation therebetween. In the illustrated embodiment, a force applied bythe second fastener 114 is transferred to the hinge pin 110 through thesecond rod R2 and through a second saddle 122 disposed between thesecond rod and the hinge pin. In other arrangements, the saddle 122 canbe omitted and the second rod R2 can bear directly against the hinge pin110. In still further arrangements, the second fastener 114 can beardirectly against the saddle 122. For example, the second fastener 114can include an outer set screw that bears against the saddle 122 to lockrelative rotation of the bodies 102, 106, and an inner set screw thatbears against the second rod R2 to secure the second rod to theconnector 100.

The geometries of the various components of the connector 100 can beconfigured such that tightening either of the fasteners 112, 114individually is effective to lock relative rotation between the bodies102, 106, or such that both fasteners 112, 114 must be tightened beforerelative rotation between the bodies 102, 106 is locked.

The ability to rotate the first and second bodies 102, 106 relative toone another about the rotation axis A1 can advantageously allow firstand second rods R1, R2 to be locked together even when the rods areobliquely angled with respect to one another, e.g., in the sagittalplane or in the coronal plane. The connector 100 can be particularlyuseful in connecting tandem rods of a spinal fixation construct acrossthe cervical-thoracic (CT) junction of a patient. For example, theconnector 100 can secure the rods R1, R2 in a laterally-offsetarrangement to accommodate the different screw trajectories that mayoccur at the CT junction. By way of further example, the ability of theconnector 100 to articulate can allow a cervical rod and a thoracic rodto be locked to one another at an oblique angle in the sagittal plane,e.g., to restore natural lordosis or kyphosis. The connector 100 canalso be particularly useful in spinal deformity correction and otherprocedures in which multiple angled rods are to be coupled to oneanother.

The first body 102 is shown in greater detail in FIGS. 1C, 1E, and 1F.The first body 102 can include proximal and distal ends 102 p, 102 dthat define a proximal-distal axis A2. The proximal end 102 p of thebody 102 can include a pair of spaced apart arms 124, 126 that definethe first rod-receiving recess 104 therebetween. A rod R1 disposed inthe first rod-receiving recess 104 can have a central longitudinal rodaxis A3. The first rod-receiving recess 104 can be open in a proximaldirection, such that a rod R1 can be inserted into the recess by movingthe rod distally with respect to the connector 100. Alternatively, thefirst rod-receiving recess 104 can be open in distal direction, open ina lateral direction, or closed such that the rod R1 must be translatedalong the axis A3 to insert the rod into the recess 104.

Each of the arms 124, 126 can extend from the distal portion 102 d ofthe body 102 to a free end. The outer surfaces of each of the arms 124,126 can include a feature (not shown), such as a recess, dimple, notch,projection, or the like, to facilitate coupling of the connector 100 tovarious instruments. For example, the outer surface of each arm 124, 126can include an arcuate groove at the respective free end of the arms forattaching the connector 100 to an extension tower or retractor. The arms124, 126 can include or can be coupled to extension or reduction tabs(not shown) that extend proximally from the body 102 to functionallyextend the length of the arms 124, 126. The extension tabs canfacilitate insertion and reduction of a rod or other implant, as well asinsertion and locking of the first fastener 112. The extension tabs canbe configured to break away or otherwise be separated from the arms 124,126.

The inner surfaces of each of the arms 124, 126 can be configured tomate with the first fastener 112. For example, the inner surfaces of thearms 124, 126 can include threads that correspond to external threadsformed on the first fastener 112. Accordingly, rotation of the firstfastener 112 with respect to the body 102 about the axis A2 can beeffective to translate the first fastener with respect to the bodyaxially along the axis A2.

The inner surfaces of each of the arms 124, 126 can include features forretaining the first saddle 118 within the first body 102 and/or forlimiting or preventing certain movement of the saddle with respect tothe body. For example, the arms 124, 126 can each include a recess 128configured to receive a corresponding projection 144 formed on thesaddle 118. Each recess 128 can define a distal-facing upper surfaceconfigured to limit proximal travel of the saddle 118 along the axis A2and a proximal-facing lower surface configured to limit distal travel ofthe saddle 118 along the axis A2. The recess 128 can extend through lessthan an entire width of the arm in which the recess is formed, such thatrotation of the saddle 118 relative to the body 102 about the axis A2 islimited or prevented when the projections 144 of the saddle are receivedwithin the recesses.

It will be appreciated that the illustrated retention features areexemplary, and that various other retention features can be used insteador in addition. For example, the structures can be reversed such thatthe body 102 includes projections received within corresponding recessesformed in the saddle 118. As another example, the saddle 118 and thebody 102 can include opposed grooves in which a snap ring or C-clip isreceived to retain the saddle to the body. As yet another example, thesaddle 118 and the hinge pin 110 can include opposed grooves in which asnap ring or C-clip is received to retain the saddle to the hinge pin.

The first body 102 can include an outer bearing surface 130 configuredto contact and bear against a corresponding bearing surface 140 of thesecond body 106. The respective bearing surfaces 130, 140 of the bodies102, 106 can bear against one another to lock relative rotation betweenthe bodies as they are urged towards one another. In the illustratedembodiment, the bearing surfaces 130, 140 of the first and second bodies102, 106 are opposed planar surfaces configured to frictionally-engageone another when the connector 100 is locked. It will be appreciated,however, that various other arrangements can be used instead or inaddition. For example, the bearing surfaces 130, 140 can include or canbe defined by complementary male and female structures of the first andsecond bodies 102, 106. In some embodiments, the first body 102 caninclude a conical male projection, an outer surface of which defines thebearing surface 130 of the first body, and the second body 106 caninclude a conical female recess, an inner surface of which defines thebearing surface 140 of the second body. As the projection of the firstbody 102 is urged into the recess of the second body 106, the conicalsurfaces wedge against one another to form a taper-lock connection.While conical surfaces are described in the example above, the male andfemale features can include concave or convex spherical surfaces,stepped surfaces, and so forth.

One or both of the bearing surfaces 130, 140 can include surfacefeatures for enhancing grip between the surfaces. For example, one orboth surfaces can include teeth, grooves, roughening, surface texturesor coatings, etc. In some embodiments, as shown in FIG. 1D, each bearingsurface 130, 140 can include a plurality of teeth that extend radiallyoutward from the rotation axis A1. The teeth can selectively interlockto maintain the bodies 102, 106 in one of a plurality of discreterotational positions relative to one another.

The distal end 102 d of the body 102 can define an interior cavity 132in which a first end of the hinge pin 110 can be received. The cavity132 can be open to the bearing surface 130 of the first body 102 andopen to the first rod-receiving recess 104 as shown. In someembodiments, the cavity 132 can be a blind bore formed in the bearingsurface 130 of the body 102 and intersecting with the firstrod-receiving recess 104. At least one dimension of the cavity 132 canbe greater than a corresponding dimension of the hinge pin 110 to allowthe hinge pin to translate within the cavity along the rotation axis A1.As described further below, the cavity 132 can be dimensioned to limitthe degree to which the body 102 can rotate relative to the hinge pin110 about the axis A1.

The second body 106 can be identical or substantially identical to thefirst body 102, or can have any of the features or variations describedabove with respect to the first body 102. Accordingly, only a briefdescription of the second body 106 is provided here for the sake ofbrevity. The second body 106 can include proximal and distal ends 106 p,106 d that define a proximal-distal axis A4. The proximal end 106 p ofthe body 106 can include a pair of spaced apart arms 134, 136 thatdefine the second rod-receiving recess 108 therebetween. A rod R2disposed in the second rod-receiving recess 108 can have a centrallongitudinal rod axis A5. The second rod-receiving recess 108 can beopen in a proximal direction, such that a rod R2 can be inserted intothe recess by moving the rod distally with respect to the connector 100.Alternatively, the second rod-receiving recess 108 can be open in distaldirection, open in a lateral direction, or closed such that the rod R2must be translated along the axis A5 to insert the rod into the recess108.

Each of the arms 134, 136 can include features 138 for retaining thesaddle 122 within the body 106. The second body 106 can include an outerbearing surface 140 configured to contact and bear against the outerbearing surface 130 of the first body 102. The distal end 106 d of thesecond body 106 can define an interior cavity 142 in which a second endof the hinge pin 110 can be received. The cavity 142 can be open to thebearing surface 140 of the second body 106 and open to the second rodrecess 108 as shown. In some embodiments, the cavity 142 can be a blindbore formed in the bearing surface 140 of the body 106 and intersectingwith the second rod recess 108. At least one dimension of the cavity 142can be greater than a corresponding dimension of the hinge pin 110 toallow the hinge pin to translate within the cavity along the rotationaxis A1. As described further below, the cavity 142 can be dimensionedto limit the degree to which the body 106 can rotate relative to thehinge pin 110 about the axis A1.

The bodies 102, 106 of the connector 100 can include various featuresfor decreasing or increasing the center-to-center offset between thefirst and second rods R1, R2 when the rods are locked to the connector.In the illustrated embodiment, the bearing surfaces 130, 140 of thefirst and second bodies 102, 106 are obliquely angled with respect tothe bodies' respective proximal-distal axes A2, A4. Accordingly, therods R1, R2 move towards one another as they are advanced distally intothe connector 100. This can advantageously reduce the center-to-centeroffset of the rods R1, R2, while preserving sufficient materialthickness at the proximal ends of the bodies 102, 106 to withstand therelatively high forces subjected to the connector 100 during rodreduction, fastener tightening, and/or post-operative patient movement.

As another example, the bearing surfaces 130, 140 of the bodies 102, 106can be parallel to the proximal-distal axes A2, A4, and instead the rodrecesses 104, 108 can be obliquely angled or can follow a curved pathwith respect to the proximal-distal axes to bring the rods R1, R2 closertogether.

As another example, the axis along which the first fastener 112 advancesas it is tightened can be offset laterally from the first rod axis A3when the first rod R1 is fully seated in the recess 104, or can beobliquely angled with respect to the proximal-distal axis A2 of thefirst body 102. Alternatively, or in addition, the axis along which thesecond fastener 114 advances as it is tightened can be offset laterallyfrom the second rod axis A5 when the second rod R2 is fully seated inthe recess 108, or can be obliquely angled with respect to theproximal-distal axis A4 of the second body 106.

The rotation axis A1 of the connector 100 can be perpendicular to therod axis A3 and perpendicular to the rod axis A5. The rotation axis A1can be perpendicular to the proximal-distal axis A2 of the first body,or can be obliquely angled with respect to the axis A2. The rotationaxis A1 can be perpendicular to the proximal-distal axis A4 of thesecond body, or can be obliquely angled with respect to the axis A4. Theproximal-distal axes A2, A4 of the bodies 102, 106 can be parallel toone another or can extend at an oblique angle with respect to oneanother.

The first saddle 118 is shown in greater detail in FIGS. 1C, 1G, and 1H.The saddle 118 can be positioned within the body 102. The saddle 118 canbe configured to translate within the body 102 along the axis A2, e.g.,between proximal and distal limits defined by the interaction betweenthe recesses 128 of the body 102 and projections 144 formed on thesaddle.

The saddle 118 can be generally cylindrical with first and second arms146, 148 extending in a proximal direction to respective free ends ofthe arms. The first and second arms 146, 148 can be aligned with thefirst and second arms 124, 126 of the body 102 such that a recessdefined therebetween is aligned with the first rod-receiving recess 104.Accordingly, the first rod R1 can be simultaneously cradled between thearms 146, 148 of the saddle 118 and the arms 124, 126 of the body 102when the rod is disposed in the first rod-receiving recess 104. Thefirst and second arms 146, 148 of the saddle 118 can include projections144 extending radially outward therefrom and configured to be receivedwithin the recesses 128 of the first body 102.

The distal-facing surface of the saddle 118 can define a recess 150configured to receive at least a portion of the hinge pin 110. In theillustrated embodiment, the recess 150 is semi-cylindrical. The depth ofthe recess 150 can increase along the length of the recess as shown toaccount for a body geometry in which the proximal-distal axis A2 of thebody is obliquely angled with respect to the rotation axis A1 of thehinge pin 110.

The saddle 118 can include one or more ramped, curved, or otherwisetapered surfaces configured to contact and bear against a counterpartsurface of the hinge pin 110. For example, a depression formed in theouter surface of the first arm 146 of the saddle 118 can define a firstbearing surface 152 that is a section of a cone. A depression formed inthe outer surface of the second arm 148 of the saddle 118 can define asecond bearing surface 154 that is a section of a cone.

The second saddle 122 can be identical or substantially identical to thefirst saddle 118, or can have any of the features or variationsdescribed above with respect to the first saddle 118. Accordingly, onlya brief description of the second saddle 122 is provided here for thesake of brevity. The second saddle 122 can be positioned within the body106. The saddle 122 can be configured to translate within the body 106along the axis A4, e.g., between proximal and distal limits defined bythe interaction between the recesses 138 of the body and projections 156formed on the saddle.

The saddle 122 can be generally cylindrical with first and second arms158, 160 extending in a proximal direction to respective free ends ofthe arms. The first and second arms 158, 160 can be aligned with thefirst and second arms 134, 136 of the body 106 such that a recessdefined therebetween is aligned with the second rod-receiving recess108. Accordingly, the second rod R2 can be simultaneously cradledbetween the arms 158, 160 of the saddle 122 and the arms 134, 136 of thebody 106 when the rod is disposed in the second rod-receiving recess108. The first and second arms 158, 160 of the saddle 122 can includeprojections 156 extending radially outward therefrom and configured tobe received within the recesses 138 of the second body 106.

The distal-facing surface of the saddle 122 can define a recess 162configured to receive at least a portion of the hinge pin 110. In theillustrated embodiment, the recess 162 is semi-cylindrical. The depth ofthe recess 162 can increase along the length of the recess as shown toaccount for a body geometry in which the proximal-distal axis A4 of thebody 106 is obliquely angled with respect to the rotation axis A1 of thehinge pin 110.

The saddle 122 can include one or more ramped, curved, or otherwisetapered surfaces configured to contact and bear against a counterpartsurface of the hinge pin 110. For example, a depression formed in theouter surface of the first arm 158 of the saddle 122 can define a firstbearing surface 164 that is a section of a cone. A depression formed inthe outer surface of the second arm 160 of the saddle 122 can define abearing surface 166 that is a section of a cone.

The first fastener 112 can include an exterior thread configured to matewith the interior threads formed on the arms 124, 126 of the body 102 toallow the first fastener to be advanced or retracted along the axis A2with respect to the body by rotating the first fastener about the axisA2. The first fastener 112 can include a driving interface 168configured to receive a driver for applying a rotational force to thefirst fastener about the axis A2. The distal surface of the firstfastener 112 can be configured to contact and bear against a rod R1disposed in the first rod-receiving 104 recess to lock the rod to theconnector 100. When tightened against the rod R1, the first fastener 112can prevent the rod from translating relative to the connector 100 alongthe axis A3 and/or from rotating with respect to the connector about theaxis A3. While a unitary set screw 112 is shown, it will be appreciatedthat other fasteners can be used instead or addition, such as a closurecap that advances and locks by quarter-turn rotation, a closure cap thatslides in laterally without rotating, a nut that threads onto anexterior of the body, or a dual-component set screw withindependently-rotatable inner and outer members, the inner member actingon the rod R1 and the outer member acting on the saddle 118.

The second fastener 114 can include an exterior thread configured tomate with the interior threads formed on the arms 134, 136 of the secondbody 106 to allow the second fastener to be advanced or retracted alongthe axis A4 with respect to the body by rotating the second fastenerabout the axis A4. The second fastener 114 can include a drivinginterface 170 configured to receive a driver for applying a rotationalforce to the second fastener 114 about the axis A4. The distal surfaceof the second fastener 114 can be configured to contact and bear againsta rod R2 disposed in the second rod-receiving 108 recess to lock the rodto the connector 100. When tightened against the rod R2, the secondfastener 114 can prevent the rod from translating relative to theconnector 100 along the axis A5 and/or from rotating with respect to theconnector about the axis A5. While a unitary set screw 114 is shown, itwill be appreciated that other fasteners can be used instead oraddition, such as a closure cap that advances and locks by quarter-turnrotation, a closure cap that slides in laterally without rotating, a nutthat threads onto an exterior of the body, or a dual-component set screwwith independently-rotatable inner and outer members, the inner memberacting on the rod R2 and the outer member acting on the saddle 122.

The hinge pin 110 is shown in greater detail in FIGS. 1I-1L. As shown,the hinge pin 110 can include opposed first and second ends that definea central longitudinal axis A6 extending therebetween. The longitudinalaxis A6 can be collinear with the rotation axis A1 of the connector 100.The hinge pin 110 can be formed as a substantially cylindrical shaftwith one or more protrusions 172 extending radially outward therefrom.One or both side surfaces of the protrusions 172 can be ramped, curved,or otherwise tapered and configured to contact and bear againstcounterpart surfaces of the saddles 118, 122 or, in embodiments in whichthe saddles are omitted, against counterpart surfaces of the rods R1,R2. The illustrated hinge pin 110 includes at least first and secondprotrusion surfaces 116, 120 that each form sections of respectivecones. The middle protrusion 172 of the hinge pin 110 can help keep thehinge pin centered in the cavities 132, 142 and maintain the bodies 102,106 in a position in which the bearing surfaces 130, 140 are parallel.

The protrusions 172 can extend around less than an entire circumferenceof the hinge pin 110, such that the protrusions have a non-cylindricalcross-section in a plane transverse to the axis A6. For example, asshown in FIG. 1J, each protrusion can define a lobe shape with first andsecond flat segments 172A, 172B joined by an arc 172C. The cavities 132,142 formed in the bodies 102, 106 can have a corresponding shape, onlywith an arc that extends a greater degree about the circumference of thehinge pin 110. Accordingly, when the protrusions 172 are received withinthe cavities 132, 142, the degree to which the bodies 102, 106 are ableto rotate relative to the hinge pin 110 about the axis A1 is limited tothe difference between the arc length of the protrusions and the arclength of the cavity.

The connector 100 can be assembled by inserting one end of the hinge pin110 into the cavity 132 of the first body 102 and the other end of thehinge pin into the cavity 142 of the second body 106. The saddles 118,122 can be inserted into the proximal ends of the bodies 102, 106 andadvanced distally until the projections 144, 156 of the saddles snapinto the grooves 128, 138 of the bodies to retain the saddles therein.At this stage of assembly, even before locking rods within the connector100, the saddles 118, 122 can interfere with the protrusions 172 of thehinge pin 110 to prevent the hinge pin from being removed from either ofthe first and second bodies 102, 106.

A first rod R1 can be seated in the first rod recess 104 and secured tothe connector 100 by tightening the first fastener 112. As the firstfastener 112 is tightened, the first rod R1 can be urged distallyagainst the saddle 118, in turn urging the saddle distally against thehinge pin 110. As the saddle 118 is urged distally, the female conicalsurface 152 of the saddle bears against the male conical surface 116 ofthe hinge pin protrusion 172, applying a force to the hinge pin 110 thaturges the hinge pin deeper into the cavity 132.

A second rod R2 can be seated in the second rod recess 108 and securedto the connector 100 by tightening the second fastener 114. As thesecond fastener 114 is tightened, the second rod R2 can be urgeddistally against the saddle 122, in turn urging the saddle distallyagainst the hinge pin 110. As the saddle 122 is urged distally, thefemale conical surface 166 of the saddle bears against the male conicalsurface 120 of the hinge pin protrusion 172, applying a force to thehinge pin 110 that urges the hinge pin deeper into the cavity 142.

Before fully tightening one or both fasteners 112, 114, the bodies 102,106 can be rotated relative to one another about the axis A1 as desiredby the user. The fasteners 112, 114 can then be tightened to lock suchrelative rotation. In particular, the opposing forces applied to thehinge pin 110 by the saddles 118, 122 as the fasteners 112, 114 aretightened can cause the bodies 102, 106 to translate relative to oneanother along the axis A1, urging the bearing surfaces 130, 140 of thebodies into engagement with each other. Friction, mechanical interlock,or other forces between the bearing surfaces 130, 140 can be effectiveto lock relative rotation of the bodies 102, 106 about the axis A1.

FIGS. 2A-2E illustrate an exemplary embodiment of a connector 200. Asshown, the connector 200 can include a first body 202 that defines afirst rod-receiving recess or channel 204 and a second body 206 thatdefines a second rod-receiving recess or channel 208. The first andsecond bodies 202, 206 can be connected to one another at least in partby a hinge pin 210. The hinge pin 210 can define a rotation axis A1about which the first and second bodies 202, 206 can rotate relative toone another. The connector 200 can include first and second fasteners212, 214 configured to secure respective first and second rods R1, R2 orother fixation elements to the connector 200.

At least one of the fasteners 212, 214 can further be configured to urgethe first and second bodies 202, 206 towards one another and therebylock relative rotation of the first and second bodies about the rotationaxis A1. For example, the first fastener 212 can be tightened to securea first rod R1 within the first body 202 and to apply a force to a firstramped, curved, or otherwise tapered surface 216 of the hinge pin 210 todraw the first and second bodies 202, 206 towards one another, lockingrotation therebetween. In the illustrated embodiment, a force applied bythe first fastener 212 is transferred to the hinge pin 210 through thefirst rod R1. In other arrangements, a saddle of the type describedabove can be disposed between the first rod R1 and the hinge pin 210. Instill further arrangements, the first fastener 212 can bear directlyagainst a saddle. For example, the first fastener 212 can include anouter set screw that bears against a saddle to lock relative rotation ofthe bodies 202, 206, and an inner set screw that bears against the firstrod R1 to secure the first rod to the connector 200.

The second fastener 214 can be tightened to secure a second rod R2within the second body 206. The second fastener 214 can bear directlyagainst the second rod R2, or against an intermediate rod pusher 222 asshown.

The ability to rotate the first and second bodies 202, 206 relative toone another about the rotation axis A1 can advantageously allow firstand second rods R1, R2 to be locked together even when the rods areobliquely angled with respect to one another, e.g., in the sagittalplane or in the coronal plane. The connector 200 can be particularlyuseful in connecting tandem rods of a spinal fixation construct acrossthe cervical-thoracic (CT) junction of a patient. For example, theconnector 200 can secure the rods R1, R2 in a laterally-offsetarrangement to accommodate the different screw trajectories that mayoccur at the CT junction. By way of further example, the ability of theconnector 200 to articulate can allow a cervical rod and a thoracic rodto be locked to one another at an oblique angle in the sagittal plane,e.g., to restore natural lordosis or kyphosis. The connector 200 canalso be particularly useful in spinal deformity correction and otherprocedures in which multiple angled rods are to be coupled to oneanother.

The first body 202 can include proximal and distal ends 202 p, 202 dthat define a proximal-distal axis A2. The proximal end 202 p of thebody 202 can include a pair of spaced apart arms 224, 226 that definethe first rod-receiving recess 204 therebetween. A rod R1 disposed inthe first rod-receiving recess 204 can have a central longitudinal rodaxis A3. The first rod-receiving recess 204 can be open in a proximaldirection, such that a rod R1 can be inserted into the recess by movingthe rod distally with respect to the connector 200. Alternatively, thefirst rod-receiving recess 204 can be open in distal direction, open ina lateral direction, or closed such that the rod R1 must be translatedalong the axis A3 to insert the rod into the recess 204.

Each of the arms 224, 226 can extend from the distal portion 202 d ofthe body 202 to a free end. The outer surfaces of each of the arms 224,226 can include a feature (not shown), such as a recess, dimple, notch,projection, or the like, to facilitate coupling of the connector 200 tovarious instruments. For example, the outer surface of each arm 224, 226can include an arcuate groove at the respective free end of the arms forattaching the connector 200 to an extension tower or retractor. The arms224, 226 can include or can be coupled to extension or reduction tabs(not shown) that extend proximally from the body 202 to functionallyextend the length of the arms 224, 226. The extension tabs canfacilitate insertion and reduction of a rod or other implant, as well asinsertion and locking of the first fastener 212. The extension tabs canbe configured to break away or otherwise be separated from the arms 224,226.

The inner surfaces of each of the arms 224, 226 can be configured tomate with the first fastener 212. For example, the inner surfaces of thearms 224, 226 can include threads that correspond to external threadsformed on the first fastener 212. Accordingly, rotation of the firstfastener 212 with respect to the body 202 about the axis A2 can beeffective to translate the first fastener with respect to the bodyaxially along the axis A2.

The first body 202 can include an outer bearing surface 230 configuredto contact and bear against a corresponding bearing surface 240 of thesecond body 206. The respective bearing surfaces 230, 240 of the bodies202, 206 can bear against one another to lock relative rotation betweenthe bodies as they are urged towards one another. In the illustratedembodiment, the bearing surfaces 230, 240 of the first and second bodies202, 206 are defined by complementary male and female structures of thefirst and second bodies 202, 206. As shown, the first body 202 caninclude a conical male projection, an outer surface of which defines thebearing surface 230 of the first body, and the second body 206 caninclude a conical female recess, an inner surface of which defines thebearing surface 240 of the second body. As the projection of the firstbody 202 is urged into the recess of the second body 206, the conicalsurfaces 230, 240 wedge against one another to form a taper-lockconnection. While conical surfaces are described in the example above,the male and female features can include concave or convex sphericalsurfaces, stepped surfaces, and so forth. It will be appreciated thatvarious other arrangements can be used instead or in addition, such asopposed planar surfaces configured to frictionally-engage one another asin the connector 100 described above.

One or both of the bearing surfaces 230, 240 can include surfacefeatures for enhancing grip between the surfaces. For example, one orboth surfaces can include teeth, grooves, roughening, surface texturesor coatings, etc. In some embodiments, each bearing surface 230, 240 caninclude a plurality of teeth that extend radially outward from therotation axis A1. The teeth can selectively interlock to maintain thebodies 202, 206 in one of a plurality of discrete rotational positionsrelative to one another.

The distal end 202 d of the body 202 can define an interior cavity 232in which a first end of the hinge pin 210 can be received. The cavity232 can be open to the bearing surface 230 of the first body 202 andopen to the first rod-receiving recess 204 as shown. In someembodiments, the cavity 232 can be a blind bore formed in the bearingsurface 230 of the body 202 and intersecting with the firstrod-receiving recess 204. At least one dimension of the cavity 232 canbe greater than a corresponding dimension of the hinge pin 210 to allowthe hinge pin to translate within the cavity along the rotation axis A1.

The second body 202 is shown in greater detail in FIGS. 2C, 2D, and 2E.The second body 206 can include proximal and distal ends 206 p, 206 dthat define a proximal-distal axis A4. The body 206 can include a pairof spaced apart arms 234, 236 that define the second rod-receivingrecess 208 therebetween. A rod R2 disposed in the second rod-receivingrecess 208 can have a central longitudinal rod axis A5. The secondrod-receiving recess 208 can be open in a lateral direction, as shown,such that a rod R2 can be inserted into the recess by moving the rodlaterally with respect to the connector 200. Alternatively, the secondrod-receiving recess 208 can be open in a proximal direction, open in adistal direction, or closed such that the rod R2 must be translatedalong the axis A5 to insert the rod into the recess 208.

The second body 206 can include an outer bearing surface 240 configuredto contact and bear against the outer bearing surface 230 of the firstbody 202. The second body 206 can define an interior cavity 242 in whicha second end of the hinge pin 210 can be received. The cavity 242 can beopen to the bearing surface 240 of the second body 206 and open to thesecond rod recess 208 as shown. The cavity 242 can include a shoulder274 configured to limit translation of the hinge pin 210 relative to thebody 206 along the axis A1.

A rod pusher 222 can be disposed within the cavity 242 and can beconfigured to bear against the second rod R2. The rod pusher 222 can becoupled to the second body 206 by a bias element configured to bias therod pusher towards the rod R2, e.g., to provide a “snap and drag” effectwhen seating the rod in the second recess 208. Further details on suchfeatures can be found in U.S. application Ser. No. 15/158,127 filed onMay 18, 2016 and entitled “IMPLANT CONNECTORS AND RELATED METHODS,”which is hereby incorporated by reference in its entirety.

At least one of the arms 234, 236 of the second body 206 can include anopening 276 configured to receive the second fastener 214 therein. Forexample, as shown, the first arm 234 can include a threaded opening 276in which the second fastener 214 can be advanced to urge the rod pusher222 against a second rod R2 seated in the second rod-receiving recess208.

The bodies 202, 206 of the connector 200 can include various featuresfor decreasing or increasing the center-to-center offset between thefirst and second rods R1, R2 when the rods are locked to the connector.In the illustrated embodiment, the outer surface of the first body 202that opposes the second body 206 is obliquely angled with respect to theproximal-distal axis A2. Accordingly, the rods R1, R2 move towards oneanother as they are advanced into the connector 200. This canadvantageously reduce the center-to-center offset of the rods R1, R2,while preserving sufficient material thickness at the proximal end ofthe first body 202 to withstand the relatively high forces subjected tothe connector 200 during rod reduction, fastener tightening, and/orpost-operative patient movement.

As another example, the opposing outer surfaces of the bodies 202, 206can be parallel to the proximal-distal axes A2, A4, and instead the rodrecesses 204, 208 can be obliquely angled or can follow a curved pathwith respect to the proximal-distal axes to bring the rods R1, R2 closertogether.

As another example, the axis along which the first fastener 212 advancesas it is tightened can be offset laterally from the first rod axis A3when the first rod R1 is fully seated in the recess 204, or can beobliquely angled with respect to the proximal-distal axis A2 of thefirst body 202. Alternatively, or in addition, the axis along which thesecond fastener 214 advances as it is tightened can be offset laterallyfrom the second rod axis A5 when the second rod R2 is fully seated inthe recess 208, or can be obliquely angled with respect to theproximal-distal axis A4 of the second body 206.

The rotation axis A1 of the connector 200 can be perpendicular to therod axis A3 and perpendicular to the rod axis A5. The rotation axis A1can be perpendicular to the proximal-distal axis A2 of the first body,or can be obliquely angled with respect to the axis A2. The rotationaxis A1 can be perpendicular to the proximal-distal axis A4 of thesecond body, or can be obliquely angled with respect to the axis A4. Theproximal-distal axes A2, A4 of the bodies 202, 206 can be parallel toone another or can extend at an oblique angle with respect to oneanother.

The first fastener 212 can include an exterior thread configured to matewith the interior threads formed on the arms 224, 226 of the body 202 toallow the first fastener to be advanced or retracted along the axis A2with respect to the body by rotating the first fastener about the axisA2. The first fastener 212 can include a driving interface 268configured to receive a driver for applying a rotational force to thefirst fastener about the axis A2. The distal surface of the firstfastener 212 can be configured to contact and bear against a rod R1disposed in the first rod-receiving 204 recess to lock the rod to theconnector 200. When tightened against the rod R1, the first fastener 212can prevent the rod from translating relative to the connector 200 alongthe axis A3 and/or from rotating with respect to the connector about theaxis A3. While a unitary set screw 212 is shown, it will be appreciatedthat other fasteners can be used instead or addition, such as a closurecap that advances and locks by quarter-turn rotation, a closure cap thatslides in laterally without rotating, a nut that threads onto anexterior of the body, or a dual-component set screw withindependently-rotatable inner and outer members, the inner member actingon the rod R1 and the outer member acting on a saddle of the typedescribed above.

The second fastener 214 can include an exterior thread configured tomate with the interior threads formed in the first arm 234 of the secondbody 206 to allow the second fastener to be advanced or retracted alongthe axis A4 with respect to the body by rotating the second fastenerabout the axis A4. The second fastener 214 can include a drivinginterface 270 configured to receive a driver for applying a rotationalforce to the second fastener 214 about the axis A4. The distal surfaceof the second fastener 214 can be configured to contact and bear againstthe rod pusher 222 or, in embodiments in which the rod pusher isomitted, against a rod R2 disposed in the second rod-receiving 208recess to lock the rod to the connector 200. When tightened, the secondfastener 214 can prevent the rod R2 from translating relative to theconnector 200 along the axis A5 and/or from rotating with respect to theconnector about the axis A5. While a unitary set screw 214 is shown, itwill be appreciated that other fasteners can be used instead oraddition, such as a closure cap that advances and locks by quarter-turnrotation, a closure cap that slides in laterally without rotating, or anut that threads onto an exterior of the body.

The hinge pin 210 can include opposed first and second ends that definea central longitudinal axis A6 extending therebetween. The longitudinalaxis A6 can be collinear with the rotation axis A1 of the connector 200.The hinge pin 210 can be formed as a substantially cylindrical shaft.The portion of the hinge pin 210 received within the first body 202 caninclude a rod seat 278. The portion of the hinge pin 210 received withinthe second body 206 can include a protrusion 272 extending radiallyoutward therefrom.

The protrusion 272 can be seated in and can bear against the shoulder274 formed in the second body 206. Accordingly, lateral translation ofthe hinge pin 210 along the axis A1, e.g., as the first rod R1 is urgedagainst the hinge pin, can cause the second body 206 to be urged towardsthe first body to lock relative rotation therebetween. The rod seat 278can be ramped, curved, or otherwise tapered and configured to contactand bear against the first rod R1. The rod seat 278 can have a widthparallel to the axis A1 that is greater than the diameter of the firstrod R1 and/or greater than the width of the first rod-receiving recess204. The rod seat 278 can be located along the length of the hinge pin210 at a position in which a lateral sidewall 216 of the rod seatinterferes with a rod R1 as the rod is seated in the first rod-receivingrecess 204. As the rod R1 is advanced into the first rod-receivingrecess 204, it can bear against the lateral sidewall 216 of the rod seat278 to cause the hinge pin 210 to translate laterally along the axis A1,pulling the second body 206 towards the first body 202 to lock relativerotation therebetween. The hinge pin 210 can be rotatable relative tothe first and second bodies 202, 206 about the axis A1, such that thefloor of the rod seat 278 remains aligned with a floor of the firstrod-receiving recess 204 or is moved into such alignment automaticallyas a rod R1 is seated therein. Prior to seating the first rod R1, thehinge pin 210 can be retained within the cavity 232 of the first body202 using various techniques, such as swaging or a retention pin thatlimits axial translation of the hinge pin 210 relative to the bodywithout limiting rotation of the hinge pin relative to the body aboutthe axis A1.

The connector 200 can be assembled by inserting the hinge pin 210through the cavity 242 of the second body 206 to seat the protrusion 272of the hinge pin against the shoulder 274 and then installing the rodpusher 222 within the second body to retain the hinge pin therein. Thefree end of the hinge pin 210 can then be inserted into the cavity 232of the first body 202 and retained therein with a retention feature ofthe type described above. At this stage of assembly, even before lockingrods within the connector 200, the hinge pin 210 can be prevented frombeing removed from either of the first and second bodies 202, 206.

A second rod R2 can be seated in the second rod recess 208 and securedto the connector 200 by tightening the second fastener 214. As thesecond fastener 214 is tightened, the rod pusher 222 can be urgeddistally against the second rod R2 to lock the rod to the connector 200.The second body 206 can remain free to rotate relative to the first body202 about the axis A1 even after the second rod R2 is locked to theconnector 200.

A first rod R1 can be seated in the first rod recess 204 and secured tothe connector 200 by tightening the first fastener 212. As the firstfastener 212 is tightened, the first rod R1 can be urged distallyagainst the rod seat 278 of the hinge pin 210, applying a force to thehinge pin that urges the hinge pin deeper into the cavity 232.

Before fully tightening one or both fasteners 212, 214, the bodies 202,206 can be rotated relative to one another about the axis A1 as desiredby the user. The fastener 212 can then be tightened to lock suchrelative rotation. In particular, the force applied to the hinge pin 210by the first rod R1 when the fastener 212 is tightened can cause thebodies 202, 206 to translate relative to one another along the axis A1,urging the bearing surfaces 230, 240 of the bodies into engagement witheach other. Friction, mechanical interlock, or other forces between thebearing surfaces 230, 240 can be effective to lock relative rotation ofthe bodies 202, 206 about the axis A1. It will be appreciated that theconnector 200 can allow locking of the second rod R2 to the connectorand locking of the rotational degree-of-freedom of the connector to beperformed independently of one another.

FIGS. 3A-3L illustrate an exemplary embodiment of a connector 300. Asshown, the connector 300 can include a first body 302 that defines afirst rod-receiving recess or channel 304 and a second body 306 thatdefines a second rod-receiving recess or channel 308. The first andsecond bodies 302, 306 can be connected to one another at least in partby a hinge pin 310. The hinge pin 310 can define a rotation axis A1about which the first and second bodies 302, 306 can rotate relative toone another. The connector 300 can include first and second fasteners312, 314 configured to secure respective first and second rods R1, R2 orother fixation elements to the connector 300.

At least one of the fasteners 312, 314 can further be configured to urgethe first and second bodies 302, 306 towards one another and therebylock relative rotation of the first and second bodies about the rotationaxis A1. For example, the second fastener 314 can be tightened to securea second rod R2 within the second body 306 and to apply a force to aramped, curved, or otherwise tapered surface 320 of the hinge pin 310 todraw the first and second bodies 302, 306 towards one another, lockingrotation therebetween. In the illustrated embodiment, a force applied bythe second fastener 314 is transferred to the hinge pin 310 through thesecond rod R2 and through a saddle 322 disposed between the second rodand the hinge pin. In other arrangements, the saddle 322 can be omittedand the second rod R2 can bear directly against the hinge pin 310. Instill further arrangements, the second fastener 314 can bear directlyagainst the saddle 322. For example, the second fastener 314 can includean outer set screw that bears against the saddle 322 to lock relativerotation of the bodies 302, 306, and an inner set screw that bearsagainst the second rod R2 to secure the second rod to the connector 300.

The first fastener 312 can be tightened to secure a first rod R1 withinthe first body 302. The first fastener 312 can bear directly against thefirst rod R1 as shown, or against an intermediate rod pusher of the typedescribed above with respect to the connector 200.

The ability to rotate the first and second bodies 302, 306 relative toone another about the rotation axis A1 can advantageously allow firstand second rods R1, R2 to be locked together even when the rods areobliquely angled with respect to one another, e.g., in the sagittalplane or in the coronal plane. The connector 300 can be particularlyuseful in connecting tandem rods of a spinal fixation construct acrossthe cervical-thoracic (CT) junction of a patient. For example, theconnector 300 can secure the rods R1, R2 in a laterally-offsetarrangement to accommodate the different screw trajectories that mayoccur at the CT junction. By way of further example, the ability of theconnector 300 to articulate can allow a cervical rod and a thoracic rodto be locked to one another at an oblique angle in the sagittal plane,e.g., to restore natural lordosis or kyphosis. The connector 300 canalso be particularly useful in spinal deformity correction and otherprocedures in which multiple angled rods are to be coupled to oneanother.

The first body 302 is shown in greater detail in FIGS. 3C and 3G. Thefirst body 302 can include proximal and distal ends 302 p, 302 d thatdefine a proximal-distal axis A2. The proximal end 302 p of the body 302can include a pair of spaced apart arms 324, 326 that define the firstrod-receiving recess 304 therebetween. A rod R1 disposed in the firstrod-receiving recess 304 can have a central longitudinal rod axis A3.The first rod-receiving recess 304 can be open in a proximal direction,such that a rod R1 can be inserted into the recess by moving the roddistally with respect to the connector 300. Alternatively, the firstrod-receiving recess 304 can be open in distal direction, open in alateral direction, or closed such that the rod R1 must be translatedalong the axis A3 to insert the rod into the recess 304.

Each of the arms 324, 326 can extend from the distal portion 302 d ofthe body 302 to a free end. The outer surfaces of each of the arms 324,326 can include a feature (not shown), such as a recess, dimple, notch,projection, or the like, to facilitate coupling of the connector 300 tovarious instruments. For example, the outer surface of each arm 324, 326can include an arcuate groove at the respective free end of the arms forattaching the connector 300 to an extension tower or retractor. The arms324, 326 can include or can be coupled to extension or reduction tabs(not shown) that extend proximally from the body 302 to functionallyextend the length of the arms 324, 326. The extension tabs canfacilitate insertion and reduction of a rod or other implant, as well asinsertion and locking of the first fastener 312. The extension tabs canbe configured to break away or otherwise be separated from the arms 324,326.

The inner surfaces of each of the arms 324, 326 can be configured tomate with the first fastener 312. For example, the inner surfaces of thearms 324, 326 can include threads that correspond to external threadsformed on the first fastener 312. Accordingly, rotation of the firstfastener 312 with respect to the body 302 about the axis A2 can beeffective to translate the first fastener with respect to the bodyaxially along the axis A2.

The first body 302 can include an outer bearing surface 330 configuredto contact and bear against a corresponding bearing surface 340 of thesecond body 306. The respective bearing surfaces 330, 340 of the bodies302, 306 can bear against one another to lock relative rotation betweenthe bodies as they are urged towards one another. In the illustratedembodiment, the bearing surfaces 330, 340 of the first and second bodies302, 306 are defined by complementary male and female structures of thefirst and second bodies 302, 306. As shown, the first body 302 caninclude a conical male projection, an outer surface of which defines thebearing surface 330 of the first body, and the second body 306 caninclude a conical female recess, an inner surface of which defines thebearing surface 340 of the second body. As the projection of the firstbody 302 is urged into the recess of the second body 306, the conicalsurfaces 330, 340 wedge against one another to form a taper-lockconnection. While conical surfaces are described in the example above,the male and female features can include concave or convex sphericalsurfaces, stepped surfaces, and so forth. It will be appreciated thatvarious other arrangements can be used instead or in addition, such asopposed planar surfaces configured to frictionally-engage one another asin the connector 100 described above.

One or both of the bearing surfaces 330, 340 can include surfacefeatures for enhancing grip between the surfaces. For example, one orboth surfaces can include teeth, grooves, roughening, surface texturesor coatings, etc. In some embodiments, each bearing surface 330, 340 caninclude a plurality of teeth that extend radially outward from therotation axis A1. The teeth can selectively interlock to maintain thebodies 302, 306 in one of a plurality of discrete rotational positionsrelative to one another.

As described further below, the hinge pin 310 can be formed integrallywith the first body 302. The hinge pin 310 can project laterally fromthe distal end 302 d of the first body 302 along the axis A1. Thebearing surface 330 of the first body 302 can be an exterior surface ofthe integrally-formed hinge pin 310.

The second body 302 is shown in greater detail in FIGS. 3C and 3H.Except as described below, the second body 306 can be identical orsubstantially identical to the first body 302, or can have any of thefeatures or variations described above with respect to the first body302. Accordingly, only a brief description of the second body 306 isprovided here for the sake of brevity. The second body 306 can includeproximal and distal ends 306 p, 306 d that define a proximal-distal axisA4. The proximal end 306 p of the body 306 can include a pair of spacedapart arms 334, 336 that define the second rod-receiving recess 308therebetween. A rod R2 disposed in the second rod-receiving recess 308can have a central longitudinal rod axis A5. The second rod-receivingrecess 308 can be open in a proximal direction, such that a rod R2 canbe inserted into the recess by moving the rod distally with respect tothe connector 300. Alternatively, the second rod-receiving recess 308can be open in distal direction, open in a lateral direction, or closedsuch that the rod R2 must be translated along the axis A5 to insert therod into the recess 308.

Each of the arms 334, 336 can include features 338 for retaining thesaddle 322 within the body 306, e.g., of the type described above withrespect to the connector 100. The second body 306 can include an outerbearing surface 340 configured to contact and bear against the outerbearing surface 330 of the first body 302. The distal end 306 d of thesecond body 306 can define an interior cavity 342 in which a free end ofthe hinge pin 310 can be received. The cavity 342 can be open to thebearing surface 340 of the second body 306 and open to the second rodrecess 308 as shown. In some embodiments, the cavity 342 can be a blindbore formed in the bearing surface 340 of the body 306 and intersectingwith the second rod recess 308. At least one dimension of the cavity 342can be greater than a corresponding dimension of the hinge pin 310 toallow the hinge pin to translate within the cavity along the rotationaxis A1.

The bodies 302, 306 of the connector 300 can include various featuresfor decreasing or increasing the center-to-center offset between thefirst and second rods R1, R2 when the rods are locked to the connector.For example, one or both of the outer surfaces of the bodies 302, 306that oppose one another can be obliquely angled with respect to therespective proximal-distal axes A2, A4. Accordingly, the rods R1, R2 canmove towards one another as they are advanced into the connector 300.This can advantageously reduce the center-to-center offset of the rodsR1, R2, while preserving sufficient material thickness at the proximalends of the bodies 302, 306 to withstand the relatively high forcessubjected to the connector 300 during rod reduction, fastenertightening, and/or post-operative patient movement.

As another example, the opposing outer surfaces of the bodies 302, 306can be parallel to the proximal-distal axes A2, A4, and instead the rodrecesses 304, 308 can be obliquely angled or can follow a curved pathwith respect to the proximal-distal axes to bring the rods R1, R2 closertogether.

As another example, the axis along which the first fastener 312 advancesas it is tightened can be offset laterally from the first rod axis A3when the first rod R1 is fully seated in the recess 304, or can beobliquely angled with respect to the proximal-distal axis A2 of thefirst body 302. Alternatively, or in addition, the axis along which thesecond fastener 314 advances as it is tightened can be offset laterallyfrom the second rod axis A5 when the second rod R2 is fully seated inthe recess 308, or can be obliquely angled with respect to theproximal-distal axis A4 of the second body 306.

The rotation axis A1 of the connector 300 can be perpendicular to therod axis A3 and perpendicular to the rod axis A5. The rotation axis A1can be perpendicular to the proximal-distal axis A2 of the first body,or can be obliquely angled with respect to the axis A2. The rotationaxis A1 can be perpendicular to the proximal-distal axis A4 of thesecond body, or can be obliquely angled with respect to the axis A4. Theproximal-distal axes A2, A4 of the bodies 302, 306 can be parallel toone another or can extend at an oblique angle with respect to oneanother.

The saddle 322 is shown in greater detail in FIGS. 3C, 3D, 3E, and 3F.The saddle 322 can be positioned within the body 306. The saddle 322 canbe configured to translate within the body 306 along the axis A4, e.g.,between proximal and distal limits defined by the interaction betweenthe recesses 338 of the body 306 and projections 356 formed on thesaddle.

The saddle 322 can be generally cylindrical with first and second arms358, 360 extending in a proximal direction to respective free ends ofthe arms. The first and second arms 358, 360 can be aligned with thefirst and second arms 334, 336 of the body 306 such that a recessdefined therebetween is aligned with the second rod-receiving recess308. Accordingly, the second rod R2 can be simultaneously cradledbetween the arms 358, 360 of the saddle 322 and the arms 334, 336 of thebody 306 when the rod is disposed in the second rod-receiving recess308. The first and second arms 358, 360 of the saddle 322 can includeprojections 356 extending radially outward therefrom and configured tobe received within the recesses 338 of the second body 306.

The distal-facing surface of the saddle 322 can define a recess 362configured to receive at least a portion of the hinge pin 310. In theillustrated embodiment, the recess 362 is semi-cylindrical. The depth ofthe recess 362 can increase along the length of the recess to accountfor a body geometry in which the proximal-distal axis A4 of the body 306is obliquely angled with respect to the rotation axis A1 of the hingepin 310.

The saddle 322 can include one or more ramped, curved, or otherwisetapered surfaces configured to contact and bear against a counterpartsurface of the hinge pin 310. For example, a keel projection 380extending distally from the recess 362 of the saddle 322 can define afirst bearing surface 366. The first bearing surface 366 can be planar.The first bearing surface 366 can lie in a plane that is obliquelyangled with respect to the rotation axis A1. As shown in FIG. 3F, thefirst bearing surface 366 can include first and second planar portionsthat are obliquely angled relative to one another and relative to theaxis A1, and that meet at a central ridge. This can facilitate smootherramping when the connector bodies 302, 306 are rotated relative to oneanother from a neutral position.

The first fastener 312 can include an exterior thread configured to matewith the interior threads formed on the arms 324, 326 of the body 302 toallow the first fastener to be advanced or retracted along the axis A2with respect to the body by rotating the first fastener about the axisA2. The first fastener 312 can include a driving interface 368configured to receive a driver for applying a rotational force to thefirst fastener about the axis A2. The distal surface of the firstfastener 312 can be configured to contact and bear against a rod R1disposed in the first rod-receiving 304 recess to lock the rod to theconnector 300. When tightened against the rod R1, the first fastener 312can prevent the rod from translating relative to the connector 300 alongthe axis A3 and/or from rotating with respect to the connector about theaxis A3. While a unitary set screw 312 is shown, it will be appreciatedthat other fasteners can be used instead or addition, such as a closurecap that advances and locks by quarter-turn rotation, a closure cap thatslides in laterally without rotating, or a nut that threads onto anexterior of the body.

The second fastener 314 can include an exterior thread configured tomate with the interior threads formed on the arms 334, 336 of the secondbody 306 to allow the second fastener to be advanced or retracted alongthe axis A4 with respect to the body by rotating the second fastenerabout the axis A4. The second fastener 314 can include a drivinginterface 370 configured to receive a driver for applying a rotationalforce to the second fastener 314 about the axis A4. The distal surfaceof the second fastener 314 can be configured to contact and bear againsta rod R2 disposed in the second rod-receiving 308 recess to lock the rodto the connector 300. When tightened against the rod R2, the secondfastener 314 can prevent the rod from translating relative to theconnector 300 along the axis A5 and/or from rotating with respect to theconnector about the axis A5. While a unitary set screw 314 is shown, itwill be appreciated that other fasteners can be used instead oraddition, such as a closure cap that advances and locks by quarter-turnrotation, a closure cap that slides in laterally without rotating, a nutthat threads onto an exterior of the body, or a dual-component set screwwith independently-rotatable inner and outer members, the inner memberacting on the rod R2 and the outer member acting on the saddle 322.

The hinge pin 310 can include opposed first and second ends that definea central longitudinal axis A6 extending therebetween. The longitudinalaxis A6 can be collinear with the rotation axis A1 of the connector 300.The hinge pin 310 can be formed integrally or monolithically with thefirst body 302 as shown, or can be fixedly attached thereto, e.g., bywelding or other processes. A free end of the hinge pin 310 can bereceived within the second body 306. The portion of the hinge pin 310received within the second body 306 can include a slot 382 formedtherein in which the keel 380 of the saddle 322 can be received. One ormore sidewalls of the slot 382 can be ramped, curved, or otherwisetapered and configured to contact and bear against a counterpart surfaceof the saddle 322 or, in embodiments in which the saddle 322 is omitted,against a counterpart surface of the second rod R2. The illustratedhinge pin 310 includes a ramped bearing surface 320 configured tocontact and bear against the bearing surface 366 of the saddle 322 asthe second fastener 314 is tightened. The bearing surface 320 can beplanar. The bearing surface 320 can lie in a plane that is obliquelyangled with respect to the rotation axis A1.

As the second fastener 314 is tightened, the saddle 322 can be urgeddistally to translate the keel 380 distally within the slot 382. As thekeel 380 moves within the slot 382, the bearing surface 366 of the keelcan be urged along the counterpart bearing surface 320 of the hinge pin310, causing the hinge pin to translate laterally within the cavity 342of the second body 306 along the axis A1, thereby pulling the first body302 towards the second body to lock relative rotation therebetween.

The distal end of the keel 380 can be tapered or bulleted to facilitateinsertion of the keel into the slot 382. Insertion of the keel 380 intothe slot 382 of the hinge pin 310 can prevent the hinge pin from beingremoved from the second body 306, thereby retaining the first and secondbodies 302, 306 to one another, even before one or both rods R1, R2 arelocked to the connector 300. Interaction between the keel 380 and theslot 382 can also be effective to limit the range of articulationbetween the first and second bodies 302, 306. For example, the slot 382can have a width in a direction perpendicular to the axis A1 andperpendicular to the axis A4 that is greater than a corresponding widthof the keel 380. The degree to which the bodies 302, 306 can rotaterelative to one another about the axis A1 can be limited by thedifference between the width of the slot 382 and the width of the keel380.

The connector 300 can be assembled by inserting the free end of thehinge pin 310 into the cavity 342 of the second body 306. The saddle 322can be inserted into the proximal end of the second body 306 andadvanced distally until the projections 356 of the saddle snap into thegrooves 338 of the second body 306 to retain the saddle therein. At thisstage of assembly, even before locking rods within the connector 300,the saddle 322 can interfere with the slot 382 of the hinge pin 310 toprevent the hinge pin from being removed from the second body 306.

A first rod R1 can be seated in the first rod recess 304 and secured tothe connector 300 by tightening the first fastener 312. The second body306 can remain free to rotate relative to the first body 302 about theaxis A1 even after the first rod R1 is locked to the connector 300.

A second rod R2 can be seated in the second rod recess 308 and securedto the connector 300 by tightening the second fastener 314. As thesecond fastener 314 is tightened, the second rod R2 can be urgeddistally against the saddle 322, in turn urging the saddle distallyagainst the hinge pin 310. As the saddle 322 is urged distally, theramped surface 366 of the saddle bears against the ramped surface 320 ofthe slot 382 in the hinge pin 310, applying a force to the hinge pinthat urges the hinge pin deeper into the cavity 342.

Before fully tightening one or both fasteners 312, 314, the bodies 302,306 can be rotated relative to one another about the axis A1 as desiredby the user. The fastener 314 can then be tightened to lock suchrelative rotation. In particular, the force applied to the hinge pin 310by the saddle 322 when the fastener 314 is tightened can cause thebodies 302, 306 to translate relative to one another along the axis A1,urging the bearing surfaces 330, 340 of the bodies into engagement witheach other. Friction, mechanical interlock, or other forces between thebearing surfaces 330, 340 can be effective to lock relative rotation ofthe bodies 302, 306 about the axis A1. It will be appreciated that theconnector 300 can allow locking of the first rod R1 to the connector andlocking of the rotational degree-of-freedom of the connector to beperformed independently of one another.

While a single, centrally-mounted keel 380 is described above, it willbe appreciated that other configurations are possible. For example, asshown in FIGS. 3I-3L, the saddle 322 can include first and second keels380A, 380B spaced apart from one another in the width dimension of thesaddle. As also shown, the slot of the hinge pin 310 can be replacedwith first and second slots 382A, 382B that form a reduced-width portionor central rib 384 of the hinge pin configured to be received betweenthe keels 380A, 380B of the saddle 322 when the connector 300 isassembled. Each keel 380A, 380B can include a ramped, curved, orotherwise tapered bearing surface that contacts and bears against acorresponding surface of the hinge pin 310 adjacent the central rib 384.The relative widths of the rib 384 and the space between the keels 380A,380B can be selected to limit the degree to which the first body 302 canrotate relative to the second body 306 about the axis A1.

FIGS. 4A-4F illustrate an exemplary embodiment of a connector 400. Asshown, the connector 400 can include a first body 402 that defines afirst rod-receiving recess or channel 404 and a second body 406 thatdefines a second rod-receiving recess or channel 408. The first andsecond bodies 402, 406 can be connected to one another at least in partby a hinge pin 410. The hinge pin 410 can define a rotation axis A1about which the first and second bodies 402, 406 can rotate relative toone another. The connector 400 can include first and second fasteners412, 414 configured to secure respective first and second rods R1, R2 orother fixation elements to the connector 400.

At least one of the fasteners 412, 414 can further be configured to urgethe first and second bodies 402, 406 towards one another and therebylock relative rotation of the first and second bodies about the rotationaxis A1. For example, the second fastener 414 can be tightened to securea second rod R2 within the second body 406 and to apply a force to aramped, curved, or otherwise tapered surface 420 of the hinge pin 410 todraw the first and second bodies 402, 406 towards one another, lockingrotation therebetween. In the illustrated embodiment, a force applied bythe second fastener 414 is transferred to the hinge pin 410 through thesecond rod R2. The first fastener 412 can be tightened to secure a firstrod R1 within the first body 402. The first fastener 412 can beardirectly against the first rod R1 as shown, or against an intermediaterod pusher of the type described above with respect to the connector200.

Except as indicated below and as will be readily appreciated by onehaving ordinary skill in the art in view of the present disclosure, thestructure and operation of the connector 400 is the same as theconnector 300 described above, and therefore a detailed description isomitted here for the sake of brevity.

As shown, the connector 400 can omit a saddle component, such that thesecond rod R2 bears directly against a rod seat 420 formed in the hingepin 410. The rod seat 420 can be ramped, curved, or otherwise tapered.The rod seat 420 can have a width parallel to the axis A1 that isgreater than the diameter of the second rod R2 and/or greater than thewidth of the second rod-receiving recess 408. The rod seat 420 can belocated along the length of the hinge pin 410 at a position in which alateral sidewall of the rod seat interferes with a rod R2 as the rod isseated in the second rod-receiving recess 408. As the rod R2 is advancedinto the second rod-receiving recess 408, it can bear against thelateral sidewall of the rod seat 420 to cause the hinge pin 410 totranslate along the axis A1, pulling the second body 406 towards thefirst body 402 to lock relative rotation therebetween.

The rod seat 420 can be curved in multiple planes to allow theabove-described bearing action to occur at any of a plurality ofrelative rotational positions about the axis A1 of the hinge pin 410 andthe second body 406. For example, the rod seat 420 can be curved in afirst plane defined by the axes A1, A2 and in a second plane defined bythe axes A2, A3. As shown in FIG. 4E, the rod seat can have a circularcross section in a first plane P1. As shown in FIG. 4F, the rod seat 420can have a cross section in a plane P2 perpendicular to the first planeP1 that is defined by first and second straight segments angled relativeto one another and joined by an arcuate segment.

The rod seat 420 can be configured such that approximately the same rampgeometry is presented to the rod R2, regardless of the articulationangle of the first and second bodies 402, 406. The degree of curvatureof the rod seat 420 in the second plane P2 can be configured to limitarticulation of the first and second bodies 402, 406.

The hinge pin 410 can be retained within the second body 406 usingvarious techniques, such as swaging or a retention pin that limits axialtranslation of the hinge pin relative to the body while still permittingrotation of the hinge pin relative to the second body. In theillustrated embodiment, the free end of the hinge pin 410 includes apost or rivet tail 486 that projects axially therefrom. The post 486 canbe received within a through-hole 488 formed in the second body 406 andthereafter swaged, deformed, flattened, or otherwise modified such thatthe post cannot be freely removed from the through-hole. The terminalend of the post 486 can be cupped or hollowed to facilitate deformationof the post during the swaging process.

FIGS. 5A-5O illustrate an exemplary embodiment of a connector 500. Asshown, the connector 500 can include a first body 510 that defines afirst rod-receiving recess or channel 512 and a second body 580 thatdefines a second rod-receiving recess or channel 582. The first andsecond bodies 510, 580 can be connected to one another at least in partby a hinge pin 514 that defines a rotation axis A1 about which thebodies can rotate relative to one another. The hinge pin 514 can projectlaterally from the first body 510 to a free end. The free end of thehinge pin 514 can be received within an interior cavity 584 formed inthe second body 580, thereby coupling the first and second bodies 510,580. The connector 500 can include first and second fasteners 520, 522configured to secure first and second rods R1, R2 or other fixationelements to the connector 500 within the respective rod-receivingrecesses 512, 582. The second fastener 522 can also be configured toapply a force on the hinge pin and thereby lock the relative rotation ofthe first and second bodies 510, 580. As shown in the illustratedembodiment, the force applied by the second fastener 522 can betransferred to the hinge pin 514 through a saddle 550.

As discussed further below, to increase the locking strength of theconnector 500, the exterior surface of the hinge pin 514 can includesharp corners 516 or other surface features that bear against the innerwall of the cavity 584 of the second body 580. As force is applied bythe second fastener 522 to the hinge pin 514, the corners 516 of the pinmay cut into or otherwise deform the inner wall of the cavity 584, andthereby increase the resistance of the connector bodies 510, 580 torotation. The hinge pin 514 of the first body 510 can include a slot 518configured to receive a distal projection of a saddle 550 disposed inthe second rod-receiving recess 582, thereby preventing disassembly ofthe first and second bodies 510, 580 and limiting the relative rotationbetween the first and second bodies 510, 580.

The first body 510 of the connector 500, including the hinge pin 514, isshown in greater detail in FIGS. 5C through 5F. The first body 510 caninclude proximal and distal ends 510 p, 510 d that define aproximal-distal axis A2. The proximal end 510 p of the body 510 caninclude a pair of spaced apart arms 524, 526 that extend from the distalportion 510 d of the body 510 to a free end. The spaced apart arms 524,526 can define the first rod-receiving recess 512 therebetween. Thefirst rod-receiving recess 512 can be open in a proximal direction, suchthat a rod R1 can be inserted into the recess by moving the rod distallywith respect to the connector 500. Alternatively, the firstrod-receiving recess 512 can be open in distal direction, open in alateral direction, or closed such that the rod R1 must be translatedalong the axis A3 to insert the rod into the recess 512.

The hinge pin 514 can project along the rotation axis A1 from an outersurface 528 of the arm 526. As shown in the illustrated embodiment, theouter surface 528 of the arm 526 can extend vertically from the distalend 510 d of the first body 510. The hinge pin 514 can extendperpendicular from a distal end portion of the outer surface 528 of thearm 526. The hinge pin 514 can include opposed first and second endsthat define a central longitudinal axis A6 extending therebetween. Thelongitudinal axis A6 can be collinear with the rotation axis A1 of theconnector 500. The hinge pin 514 can be formed integrally ormonolithically with the first body 510 as shown, or can be fixedlyattached thereto, e.g., by welding or other processes.

The hinge pin 514 can have an exterior surface that includes sharpcorners 516 radially disposed at least partially about a perimeter ofthe pin. As discussed further below, when the hinge pin is locked down,the sharp corners 516 of the pin can cut into and/or deform an innerwall of the cavity 584 of the second body 580, thereby increasing thelocking strength of the connector 500 through edge loading. For example,through such edge loading, the sharp corners 516 of the hinge pin 514can create additional friction, mechanical interlock, or increase theradial force applied by the pin against the second body 580 toeffectively lock relative rotation of the bodies 510, 580 about the axisA1. The corners 516 of the hinge pin 514 can be formed by planar surfacesegments 530 that extend longitudinally at least partially around thepin. Each of the planar surface segments 530 can be obliquely angledwith respect to one or more adjacent planar surface segments, such thatthe planar surface segments 530 intersect with each other to form thesharp corners 516 of the hinge pin 514.

As shown in FIG. 5E, the hinge pin 514 can have five (5) planar surfacesegments 530 that form the lateral and distal surfaces of the pin. Theplanar segments 530 can intersect obliquely at their respective edgessuch that the corners 516 of hinge pin 514 form a cross sectionalprofile of a partial octagon. The proximal surface 532 of the hinge pin514 can have a rounded, curved, ramped or other contoured shape. It willbe appreciated that, in some embodiments, the planar surface segments530 can form the exterior surface of the hinge pin 514, such that thesharp corners 516 are radially disposed about the entire circumferenceof the pin. In some embodiments, more than five (5) planar surfacesegments 530 can be used to form the corners 516 of the hinge pin 514with a cross sectional profile of a polygon or portion thereof. In someembodiments, less than five planar surface segments can be used to formthe corners 516 of the hinge pin 514 with a cross sectional profile of apolygon or portion thereof.

As shown in FIGS. 5C and 5F, a slot 518 can be formed in the proximalsurface 532 of the hinge pin 514. The slot 518 can be an arcuate orrectangular shaped slot. The length of the slot 518 can be definedbetween a first pair of opposing sidewalls 540, 542. Each of theopposing sidewalls 540, 542 can lie in a plane perpendicular to therotation axis A1. The width of the slot 518 can be defined between asecond pair of sidewalls 544, 546 disposed between the first pair ofopposing sidewalls. Each of the sidewalls 544, 546 can lie in a planeperpendicular or oblique to the opposing sidewalls 540, 542 of the slot.A rib 548 can be formed in the slot 518 between the sidewalls 544, 546.As discussed further below, the slot 518 can be configured to receive adistal projection of a saddle 550 disposed in the second rod-receivingrecess 582, thereby preventing disassembly of the first and secondbodies 510, 580 and limiting the relative rotation between the first andsecond bodies 510, 580.

The second body 580 is shown in greater detail in FIGS. 5G and 5H. Thesecond body 580 can include proximal and distal ends 580 p, 580 d thatdefine a proximal-distal axis A4. The proximal end 580 p of the body 580can include a pair of spaced apart arms 586, 588 that define the secondrod-receiving recess 582 therebetween. A rod R2 disposed in the secondrod-receiving recess 582 can have a central longitudinal rod axis A5.The second rod-receiving recess 582 can be open in a proximal direction,such that a rod R2 can be inserted into the recess by moving the roddistally with respect to the connector 500. Alternatively, the secondrod-receiving recess 582 can be open in distal direction, open in alateral direction, or closed such that the rod R2 must be translatedalong the axis A5 to insert the rod into the recess 582. Each of thearms 586, 588 can include recesses or grooves 590 for retaining thesaddle 550 within the body 580. The second body 580 can include an outersurface 592 that opposes the outer surface 528 of the first body 510.

The distal end 580 d of the second body 580 can define an interiorcavity 584 in which a free end of the hinge pin 514 can be received. Thecavity 584 can be open from the outer surface 592 of the second body 580and open to the second rod recess 582. As shown in the illustratedembodiment, the cavity 584 can be a blind bore formed in the outersurface 592 of the body 580 and intersecting with the second rod recess582. In some embodiments, the cavity 584 can be a through bore. At leastone dimension of the cavity 584 can be greater than a correspondingdimension of the hinge pin 514 to allow the hinge pin to translatewithin the cavity along the rotation axis A1.

The saddle 550 is shown in greater detail in FIGS. 5I through 5L. Thesaddle 550 can be positioned within the second body 580. The saddle 550can be generally cylindrical with first and second arms 554, 556extending in a proximal direction to respective free ends of the arms.The first and second arms 554, 556 can define a rod-receiving recess orrod seat 558 therebetween. The first and second arms 554, 556 of thesaddle 550 can be aligned with the first and second arms 586, 588 of thesecond body 580 such that rod seat 558 is aligned with the secondrod-receiving recess 582. Accordingly, the second rod R2 can besimultaneously cradled between the arms 554, 556 of the saddle 550 andthe arms 586, 588 of the second body 580 when the rod R2 is disposed inthe second rod-receiving recess 582. The first and second arms 554, 556of the saddle 550 can include projections 560 (e.g., spring tabs)extending radially outward therefrom and configured to be receivedwithin the grooves or other recesses 590 of the second body 580. Thesaddle 550 can be configured to translate within the body 580 along theaxis A4, e.g., between proximal and distal limits defined by theinteraction between the grooves or recesses 590 of the second body 580and the radial projections 560 of the arms 554, 556.

As shown in FIGS. 5J through 5L, the saddle 550 can have a recesseddistal-facing bearing surface 562 and a saddle projection 552 extendingdistally therefrom. The recessed bearing surface 562 can have a curvedor other suitable shape configured to contact and bear against asemi-cylindrical, exterior surface of the hinge pin 514. The distalsaddle projection 552 can be configured to be received within the slot518 of the hinge pin 514, and thereby maintain coupling of the firstbody 510 and the second body 580. The distal saddle projection 552 canalso be configured to interfere with the slot 518 as the hinge pin 514rotates, thereby limiting the rotation range of the first body 510relative to the second body 580.

As shown in the illustrated embodiment, the distal saddle projection 552can be centrally disposed within the recessed bearing surface 562. Thedistal saddle projection 552 can have lateral-facing bearing surfaces564, 566 extending distally from the recess. The lateral-facing bearingsurfaces 564, 566 of the saddle projection can lie in a plane that isperpendicular with respect to the recessed bearing surface 562 and therotation axis A1. The lateral-facing bearing surfaces 564, 566 of thesaddle projection can be planar or curved. The lateral-facing bearingsurfaces 564, 566 of the saddle projection can be configured torespectively contact and bear against the opposing sidewalls 540, 542 ofthe slot 518 of the hinge pin 514 perpendicular to the rotation axis A1,and thereby prevent disassembly of the first and second bodies 510, 580.

The lateral-facing bearing surfaces 564, 566 of the saddle projectioncan meet at a ridge 570 having a distal-facing bearing surface. Theridge 570 of the saddle projection 552 can extend perpendicular withrespect to the proximal-distal axis A4 of the second body 580. In theillustrated embodiment, the ridge 570 can include a recess 572 formed inthe distal-facing bearing surface. The recess 572 can be sized toaccommodate the rib 548 formed in the slot 518. As discussed furtherbelow, the distal-facing bearing surface of the ridge 570 adjacent tothe recess 572 can be configured to interfere with the side walls 544,546 of the slot 518 as the hinge pin 514 rotates, thereby limiting therotation range of the first body 510 relative to the second body 580.

As shown in FIG. 5M through 5O, the connector 500 can be assembled byinserting the free end of the hinge pin 514 through the opening in theouter bearing surface 592 and into the cavity 584 of the second body580. The hinge pin 514 can be oriented within the cavity 584, such thatthe slot 518 of the pin is aligned with the second rod-receiving recess582. The saddle 550 can be inserted into the proximal end 580 p of thesecond body 580 and distally advanced until the distal saddle projection552 is received in the slot 518 of the hinge pin 514. The radialprojections 560 of the saddle arms 554, 556 can snap into the grooves orrecesses 590 of the second body 580 to retain the saddle 550.

At this stage of assembly, even before locking rods within the connector500, the saddle 550 can interfere with the slot 518 of the hinge pin 514to prevent the pin from being removed from the second body 580. Forexample, when the saddle projection 552 is received in the slot 518, thelateral-facing surfaces 564, 566 of the saddle projection can bearagainst the opposing sidewalls 540, 542 of the slot to prevent removalof the pin, and thereby maintain coupling of the first and second bodies510, 580. The distal saddle projection 552 can also interfere with theslot 518 of the hinge pin 514 to limit the relative rotation of theconnector bodies 510, 580. For example, as shown in FIG. 5N, when thehinge pin 514 rotates clockwise or counter clockwise about the rotationaxis A1, the extent of such rotation can be restricted by one of thesidewalls 544, 546 of the slot 518 contacting the ridge 570 of thesaddle projection 552.

In the illustrated embodiment, the ridge 570 of the saddle projection552 can have a distal-facing contact surface that lies in a planeperpendicular with respect to the proximal-distal axis A4 of the secondbody. As shown, the sidewalls 544, 546 of the slot 518 can lie in acommon plane. When the saddle projection 552 is disposed within the slot518, a gap can be formed between the planar contact surfaces of theridge 570 and the slot 518, thereby enabling the hinge pin 514 to rotatewithin the limits defined therebetween.

In some embodiments, a recess 572 can be formed in the ridge 570 that issized to at least partially receive a rib 548 disposed between thesidewalls 544, 546 of the slot. Such embodiments can facilitate anincrease in the range of rotation of the hinge pin 514 without acorresponding increase in the width of the gap. Alternatively oradditionally, such embodiments can facilitate a decrease the width ofthe gap without a corresponding decrease in the range of rotation of thehinge pin. In some embodiments, the sidewalls 544, 546 of the slot canlie in respective planes that intersect obliquely to increase ordecrease the range of rotation of the pin.

In some embodiments, the interaction between the slot 518 of the hingepin 514 and the saddle projection 552 can limit the range of rotation ofthe pin symmetrically with respect to the rotation axis A1. For example,in some embodiments, the range of rotation of the hinge pin 514 can belimited to ±30 degrees, ±60 degrees, ±180 degrees, or other symmetricalrange suitable depending on the surgical procedure. In some embodiments,the interaction between the slot 518 of the hinge pin 514 and the saddleprojection 552 can limit the range of rotation of the pin asymmetricallywith respect to the rotation axis A1. Limiting the range of rotation ofthe pin 514 by forming a smaller slot 518 can allow more material to beretained on the pin, thereby increasing the strength of the pin.

A first rod R1 can be seated in the first rod receiving recess 512 ofthe first body 510 and secured to the connector 500 by tightening thefirst fastener 520. The first fastener 520 can include an exteriorthread configured to mate with the interior threads formed on the arms524, 526 of the first body 510 to allow the first fastener to beadvanced or retracted along the axis A2 with respect to the body byrotating the first fastener about the axis A2. The first fastener 520can include a driving interface configured to receive a driver forapplying a rotational force to the first fastener about the axis A2.While a unitary set screw 520 is shown, it will be appreciated thatother fasteners can be used instead or addition, such as a closure capthat advances and locks by quarter-turn rotation, a closure cap thatslides in laterally without rotating, or a nut that threads onto anexterior of the body.

The distal surface of the first fastener 520 can be configured tocontact and bear against a rod R1 disposed in the first rod-receivingrecess 512 to lock the rod to the connector 500. When tightened againstthe rod R1, the first fastener 520 can prevent the rod from translatingrelative to the connector 500 along the axis A3 and/or from rotatingwith respect to the connector about the axis A3. The first rod R1 can beseated in the first rod-receiving recess 512, while the second body 580can remain free to rotate relative to the first body 510 about therotation axis A1 even after the first rod R1 is locked to the connector500.

A second rod R2 can be seated in the rod seat 558 of the saddle 550disposed in the second rod receiving recess 582 of the second body 580.The second rod R2 can be secured to the connector 500 by tightening thesecond fastener 522. The second fastener 522 can include an exteriorthread configured to mate with the interior threads formed on the arms586, 588 of the second body 580 to allow the second fastener to beadvanced or retracted along the axis A4 with respect to the body byrotating the second fastener about the axis A4. The second fastener 522can include a driving interface configured to receive a driver forapplying a rotational force to the second fastener 522 about the axisA4.

The distal surface of the second fastener 522 can be configured tocontact and bear against the rod R2 disposed in the saddle 550 to lockthe rod to the connector 500. When tightened against the rod R2, thesecond fastener 522 can prevent the rod from translating relative to theconnector 500 along the axis A5 and/or from rotating with respect to theconnector about the axis A5. While a unitary set screw 522 is shown, itwill be appreciated that other fasteners can be used, instead or inaddition, such as a closure cap that advances and locks by quarter-turnrotation, a closure cap that slides in laterally without rotating, a nutthat threads onto an exterior of the body, or a dual-component set screwwith independently-rotatable inner and outer members, the inner memberacting on the rod R2 and the outer member acting on proximal free endsof the saddle arms 554, 556.

As the second fastener 522 is tightened, the second rod R2 can be urgeddistally against the saddle 550, thereby causing the saddle to urgedistally against the hinge pin 514. As shown in FIG. 5O, the recesseddistal-facing bearing surface 562 of the saddle 550, adjacent to thedistal saddle projection 552, can bear against a counter bearing surfaceof the hinge pin 514. The downward force applied by the saddle 550 canurge the pin 514 against the inner wall of the cavity 582 of the secondbody 580.

Before fully tightening one or both fasteners 520, 522, the bodies 510,580 can be rotated relative to one another about the axis A1 as desiredby the user. The second fastener 522 can then be tightened to lock suchrelative rotation. In particular, when the fastener 522 is tightened,the force applied to the hinge pin 514 by the saddle 550 can urge thesharp corners 516 of the pin to cut and/or deform the inner wall of thecavity 584 of the second body 580. Through such edge loading, the sharpcorners 516 of the hinge pin 514 can create additional friction,mechanical interlock, or increase the radial force applied by the pinagainst the second body 580 to effectively lock relative rotation of thebodies 510, 580 about the axis A1. It will be appreciated that theconnector 500 can allow locking of the first rod R1 to the connector andlocking of the rotational degree-of-freedom of the connector to beperformed independently of one another.

In other arrangements, the second fastener 522 can bear directly againstthe saddle 550. For example, the second fastener 522 can include anouter set screw that bears against the saddle arms 554, 556 to lockrelative rotation of the bodies 510, 580, and an inner set screw thatbears against the second rod R2 to secure the second rod to theconnector 500. In still further arrangements, the saddle 522 can beomitted and the second rod R2 can bear directly against the hinge pin514.

The ability to rotate the first and second bodies 510, 580 relative toone another about the rotation axis A1 can advantageously allow firstand second rods R1, R2 to be locked together even when the rods areobliquely angled with respect to one another, e.g., in the sagittalplane or in the coronal plane. The connector 500 can be particularlyuseful in connecting tandem rods of a spinal fixation construct acrossthe cervical-thoracic (CT) junction of a patient. For example, theconnector 500 can secure the rods R1, R2 in a laterally-offsetarrangement to accommodate the different screw trajectories that mayoccur at the CT junction. By way of further example, the ability of theconnector 500 to articulate can allow a cervical rod and a thoracic rodto be locked to one another at an oblique angle in the sagittal plane,e.g., to restore natural lordosis or kyphosis. The connector 500 canalso be particularly useful in spinal deformity correction and otherprocedures in which multiple angled rods are to be coupled to oneanother.

In some embodiments, the bodies 510, 580 of the connector 500 caninclude various features for decreasing or increasing thecenter-to-center offset between the first and second rods R1, R2 whenthe rods are locked to the connector. For example, one or both of theouter surfaces of the bodies 510, 580 that oppose one another can beobliquely angled with respect to the respective proximal-distal axes A2,A4. Accordingly, the rods R1, R2 can move towards one another as theyare advanced into the connector 500. This can advantageously reduce thecenter-to-center offset of the rods R1, R2, while preserving sufficientmaterial thickness at the proximal ends of the bodies 510, 580 towithstand the relatively high forces subjected to the connector 500during rod reduction, fastener tightening, and/or post-operative patientmovement.

As another example, the opposing outer surfaces of the bodies 510, 580can be parallel to the proximal-distal axes A2, A4, and instead the rodrecesses 512, 582 can be obliquely angled or can follow a curved pathwith respect to the proximal-distal axes to bring the rods R1, R2 closertogether.

As another example, the axis along which the first fastener 520 advancesas it is tightened can be offset laterally from the first rod axis A3when the first rod R1 is fully seated in the recess 512, or can beobliquely angled with respect to the proximal-distal axis A2 of thefirst body 510. Alternatively, or in addition, the axis along which thesecond fastener 522 advances as it is tightened can be offset laterallyfrom the second rod axis A5 when the second rod R2 is fully seated inthe recess 582, or can be obliquely angled with respect to theproximal-distal axis A4 of the second body 580.

The arms 524, 526 can include or can be coupled to extension orreduction tabs (not shown) that extend proximally from the body 510 tofunctionally extend the length of the arms 524, 526. The extension tabscan facilitate insertion and reduction of a rod or other implant, aswell as insertion and locking of the first fastener 520. The extensiontabs can be configured to break away or otherwise be separated from thearms 524, 526. The inner surfaces of each of the arms 524, 526 can beconfigured to mate with the first fastener 520. For example, the innersurfaces of the arms 524, 526 can include threads that correspond toexternal threads formed on the first fastener 520. Accordingly, rotationof the first fastener 520 with respect to the body 510 about the axis A2can be effective to translate the first fastener with respect to thebody axially along the axis A2. The arms 586, 588 can similarly includeor be coupled to extension or reduction tabs.

In some embodiments, the connector 500 can include various features of aunilateral locking interface, including but not limited to one or moregrooves 594 and surface projections 596. The unilateral lockinginterface enables a surgical instrument that includes a unilaterallocking mechanism (not shown) to rigidly hold onto one side of theconnector 500. Exemplary unilateral locking interfaces that can beincluded in the connector 500 are disclosed in U.S. patent applicationSer. No. 15/843,618, filed on Dec. 15, 2017, entitled “UnilateralImplant Holders and Related Methods” (now published asUS-2019-0183541-A1), the entire contents of which are herebyincorporated by reference.

FIGS. 6A-6J illustrate an exemplary embodiment of a connector 600. Asshown, the connector 600 can include a first body 610 that defines afirst rod-receiving recess or channel 612 and a second body 680 thatdefines a second rod-receiving recess or channel 682. The first andsecond bodies 610, 680 can be connected to one another at least in partby a hinge pin 614 that defines a rotation axis A1 about which thebodies can rotate relative to one another. In the illustratedembodiment, the hinge pin 614 can project laterally from the first body610 to a free end. The free end of the hinge pin 614 can be receivedwithin an interior cavity 684 formed in the second body 680. Theconnector 600 can include first and second fasteners 620, 622 configuredto secure first and second rods R1, R2 or other fixation elements to theconnector 600 within the respective rod-receiving recesses 612, 682. Thehinge pin 614 of the first body 610 can include a slot 618 configured toreceive a distal projection 652 of a saddle 650 disposed in the secondrod-receiving recess 682, thereby preventing disassembly of the firstand second bodies 610, 680 and limiting the relative rotation betweenthe first and second bodies 610, 680.

As discussed further below, to increase the locking strength of theconnector 600, the slot 618 of the pin can be obliquely angled withrespect to the rotation axis A1 of the pin. The angled slot 618 can beconfigured to receive the distal projection 652 of a saddle 650 disposedin the second rod-receiving recess 682. The distal saddle projection 652can be oriented at an oblique angle to match or coincide with the angledslot 618 of the hinge pin 614. The distal saddle projection 652 can havea wedge-shaped cross section with tapered bearing surfaces thatfacilitate wedging of the saddle projection in the slot 618 in responseto a force applied by the second fastener 622 against the rod R2 and/orsaddle 650 itself. Wedging the distal saddle projection 652 into theangled slot 618 of the hinge pin 614 can create additional friction,mechanical interlock, or increased force applied by the pin against thesecond body 680 to effectively lock relative rotation of the bodies 610,680 about the axis A1.

Except as described below or as will be readily appreciated by onehaving ordinary skill in the art, the first body 610, the second body680, the first fastener 620, and the second fastener 622 of theconnector 600 are substantially similar to the first body 510, thesecond body 580, the first fastener 520, and the second fastener 522 ofthe connector 500 described above with respect to FIGS. 5A-5O. Adetailed description of the structure and function thereof is thusomitted here for the sake of brevity. The connector 600 can include anycombination of the features of the connector 500 described above.

The first body 610 of the connector 600, including the hinge pin 614, isshown in greater detail in FIGS. 6C and 6D. The first body 610 caninclude proximal and distal ends 610 p, 610 d that define aproximal-distal axis A2. The proximal end 610 p of the body 610 caninclude a pair of spaced apart arms 624, 626 that extend from the distalportion 610 d of the body 610 to a free end. The spaced apart arms 624,626 can define the first rod-receiving recess 612 therebetween.

The hinge pin 614 can project along the rotation axis A1 from an outersurface 628 of the arm 626. The hinge pin 614 can extend perpendicularfrom a distal end portion of the outer surface 628 of the arm 626. Thehinge pin 614 can include opposed first and second ends that define acentral longitudinal axis A6 extending therebetween. The longitudinalaxis A6 can be collinear with the rotation axis A1 of the connector 600.As discussed above with respect to FIGS. 5A-5O, the exterior surface ofthe hinge pin 614 can include sharp corners 616 or other surfacefeatures that can bear against the inner wall of the cavity 684 of thesecond body 680 to increase the locking strength of the connector 600.

The slot 618 can be formed in the proximal surface of the hinge pin 614.The slot 618 of the pin can be oriented at an oblique angle with respectto the rotation axis A1 of the pin and a central longitudinal rod axisA5 of the second rod-receiving recess 682. In some embodiments, the slot618 can be oriented at an oblique angle of approximately 7 degrees withrespect to the rod axis A5. When the bodies are rotated, the obliqueangle causes the bodies to move further or closer apart in relation toeach other in the lateral direction. This additional motion creates dragand thereby increases rotational resistance in axis A1 when the firstbody is locked down. In some embodiments, the slot 618 can be orientedat an oblique angle within an approximate range between 5 and 10 degreeswith respect to the rod axis A5, inclusively.

The length of the slot 618 can be defined between a first pair ofopposing sidewalls 640, 642 that form angled cam surfaces. Each of theopposing sidewalls 640, 642 can lie in a plane that is oblique to therotation axis A1 and the rod axis A5 of the second rod-receiving recess682. The opposing sidewalls 640, 642 can lie in substantially parallelplanes or can be obliquely angled with respect to one another. The widthof the slot 618 can be defined by a proximal-facing surface 644 disposedbetween the first pair of opposing sidewalls 640, 642 of the slot. Asdiscussed further below, the slot 618 can be configured to receive thedistal projection 652 of the saddle 650 disposed in the secondrod-receiving recess 682, and thereby prevent disassembly of the firstand second bodies 610, 680 and increase the locking strength of theconnector 600 to resist relative rotation between the first and secondbodies 610, 680.

The saddle 650 is shown in greater detail in FIGS. 6E through 6J. Thesaddle 650 can be generally cylindrical with first and second arms 654,656 extending in a proximal direction to respective free ends of thearms. The first and second arms 654, 656 of the saddle 650 can define arod seat 658 therebetween. The first and second arms 654, 656 of thesaddle 650 can include projections 660 (e.g., spring tabs) extendingradially outward therefrom. The radial projections 660 can be configuredto snap into or otherwise be received within grooves or other recesses690 of the second body 680 to retain the saddle 650 therein.

The saddle 650 can have a distal-facing bearing surface 662. Thedistal-facing bearing surface 662 can have a planar, ramped, curved orother suitable contour configured to contact and bear against acounterpart bearing surface of the hinge pin 614. The saddle 650 caninclude a saddle projection 652 that extends distally from thedistal-facing bearing surface 662 to maintain coupling of the first andsecond bodies 610, 680 and to increase the locking strength of theconnector 600 to resist relative rotation of the bodies. In someembodiments, only the saddle projection 652 is configured to contact andbear against the hinge pin 614.

As shown in the illustrated embodiment, the distal saddle projection 652can be obliquely angled with respect to a central longitudinal rod axisA5 defined by the rod seat 658. The distal saddle projection 652 can beoriented at an oblique angle to match or coincide with the angle of theslot 618 of the hinge pin 614. Thus, when disposed in the second body680, the distal saddle projection 652 can be oriented at an obliqueangle with respect to the rotation axis A1 of the pin and a centrallongitudinal rod axis A5 of the second rod-receiving recess 682. Theobliquely angled geometry of the saddle projection 652 and the slot 618can provide increased resistance to relative rotation between the bodies610, 680 about the axis A1 when the connector 600 is locked.

The distal saddle projection 652 can have tapered bearing surfaces 665,667 configured to facilitate wedging of the saddle projection in theslot 618 in response to a downward force applied against the saddle 650.To facilitate wedging, the tapered bearing surfaces 665, 667 of thedistal saddle projection 652 can be angled or ramped to intersect withthe sidewalls 640, 642 of the slot 618 of the hinge pin 614 at amismatched angle. Put another way, the tapered bearing surfaces 665, 667of the distal saddle projection can lie in respective planes that areskewed relative to the opposing sidewalls 640, 642 of the slot 618.Wedging the distal saddle projection 652 into the angled slot 618 of thehinge pin 614 can create additional friction, mechanical interlock, orincreased force to effectively lock relative rotation of the bodies 610,680 about the axis A1.

As shown in FIGS. 6H through 6J, the connector 600 can be assembled byinserting the free end of the hinge pin 614 through the opening in theouter surface 692 and into the cavity 684 of the second body 680. Thehinge pin 614 can be oriented within the cavity 684, such that the slot618 of the pin is aligned with the second rod-receiving recess 682. Thesaddle 650 can be inserted into the proximal end 680 p of the secondbody 680. The saddle 650 can be configured to translate within the body680 along the axis A4 and can thus be distally advanced until the distalsaddle projection 652 is received in the slot 618 of the hinge pin 614.

In some embodiments, the saddle 650 can be configured to translatebetween proximal and distal limits defined by the interaction betweenthe grooves or recesses 690 of the second body 680 and the radialprojections 660 of the arms 654, 656. When disposed in the second body680, the first and second arms 654, 656 of the saddle 650 can be alignedwith the first and second arms 686, 688 of the second body such that rodseat 658 is aligned with the second rod-receiving recess 682.Accordingly, the second rod R2 can be simultaneously cradled between thearms 654, 656 of the saddle 650 and the arms 686, 688 of the second body680 when the rod R2 is disposed in the second rod-receiving recess 682.

At this stage of assembly, even before locking rods within the connector600, the saddle 650 can interfere with the slot 618 of the hinge pin 614to prevent the pin from being removed from the second body 680. Forexample, when the saddle projection 652 is received in the slot 618, thetapered bearing surfaces 665, 667 of the saddle projection can bearagainst the opposing sidewalls 640, 642 of the slot to prevent removalof the pin, and thereby maintain coupling of the first and second bodies610, 680.

The distal saddle projection 652 can also interfere with the slot 618 ofthe hinge pin 614 to limit the relative rotation of the connector bodies610, 680. For example, when the hinge pin 614 rotates clockwise orcounter clockwise about the rotation axis A1, the extent of suchrotation can be restricted by an outer edge 668 of the proximal-facingsurface 644 of the slot 618 contacting a ridge 670 of the saddleprojection 652. In the illustrated embodiment, the ridge 670 of thesaddle projection 652 can have a distal-facing contact surface that liesin a plane perpendicular with respect to the proximal-distal axis A4 ofthe second body. When the saddle projection 622 is disposed within theslot 618, a gap can be formed between the ridge 670 and theproximal-facing surface 644 of the slot 618, thereby enabling the hingepin 614 to rotate within the limits defined therebetween.

In some embodiments, the interaction between the slot 618 of the hingepin 614 and the saddle projection 652 can limit the range of rotation ofthe pin symmetrically with respect to the rotation axis A1. For example,in some embodiments, the range of rotation of the hinge pin 614 can belimited to ±30 degrees, ±60 degrees, ±180 degrees, or other symmetricalrange suitable depending on the surgical procedure. In some embodiments,the interaction between the slot 618 of the hinge pin 614 and the saddleprojection 652 can limit the range of rotation of the pin asymmetricallywith respect to the rotation axis A1.

A first rod R1 can be seated in the first rod receiving recess 612 ofthe first body 610 and secured to the connector 600 by tightening thefirst fastener 620. The first fastener 620 can include an exteriorthread configured to mate with the interior threads formed on the arms624, 626 of the first body 610 to allow the first fastener to beadvanced or retracted along the axis A2 with respect to the body byrotating the first fastener about the axis A2. The distal surface of thefirst fastener 620 can be configured to contact and bear against a rodR1 disposed in the first rod-receiving recess 612 to lock the rod to theconnector 600. When tightened against the rod R1, the first fastener 620can prevent the rod from translating relative to the connector 600 alongthe axis A3 and/or from rotating with respect to the connector about theaxis A3. The first rod R1 can be seated in the first rod-receivingrecess 612, while the second body 680 can remain free to rotate relativeto the first body 610 about the rotation axis A1 even after the firstrod R1 is locked to the connector 600.

A second rod R2 can be seated in the rod seat 658 of the saddle 650disposed in the second rod receiving recess 682 of the second body 680.The second rod R2 can be secured to the connector 600 by tightening thesecond fastener 622. The second fastener 622 can include an exteriorthread configured to mate with the interior threads formed on the arms686, 688 of the second body 680 to allow the second fastener to beadvanced or retracted along the axis A4 with respect to the body byrotating the second fastener about the axis A4. The distal surface ofthe second fastener 622 can be configured to contact and bear againstthe rod R2 disposed in the saddle 650 to lock the rod to the connector600. When tightened against the rod R2, the second fastener 622 canprevent the rod from translating relative to the connector 600 along theaxis A5 and/or from rotating with respect to the connector about theaxis A5.

As the second fastener 622 is tightened, the second rod R2 can be urgeddistally against the saddle 650, thereby causing the saddle projection652 to be urged distally into the slot 618 of the hinge pin 614 and lockrelative rotation of the bodies 610, 680. In other arrangements, thesecond fastener 622 can bear directly against the saddle 650. Forexample, the second fastener 622 can include an outer set screw thatbears against the saddle arms 654, 656 to lock relative rotation of thebodies 610, 680, and an inner set screw that bears against the secondrod R2 to secure the second rod to the connector 600.

Before fully tightening one or both fasteners 620, 622, the bodies 610,680 can be rotated relative to one another about the axis A1 as desiredby the user. The second fastener 622 can then be tightened to lock suchrelative rotation. In particular, the force applied by the secondfastener 622 to the saddle 650 can wedge the saddle projection 652 intothe slot 618 of the hinge pin 614. For example, as shown in FIG. 6I, thedistal saddle projection 652 can be wedged into the slot 618 of thehinge pin 614 such that the tapered bearing surfaces 665, 667 intersectwith the sidewalls 640, 642 of the slot 618 at a mismatched angle. Thedownward force applied by wedging the distal saddle projection 652 intothe angled slot 618 of the hinge pin 614 can urge the pin 614 againstthe inner wall of the cavity 684 of the second body 680, and therebyeffectively lock relative rotation of the bodies 610, 680 about the axisA1.

In some embodiments, the force applied to the hinge pin 614 by wedgingthe saddle 650 into the slot 618 of the pin can urge the sharp edges orcorners 616 of the pin to cut and/or deform the inner wall of the cavity684 of the second body 680. Through such edge loading, the sharp corners616 of the hinge pin 614 can create additional friction, mechanicalinterlock, or increase the radial force applied by the pin against thesecond body 680 to effectively lock relative rotation of the bodies 610,680 about the axis A1. It will be appreciated that the connector 600 canallow locking of the first rod R1 to the connector and locking of therotational degree-of-freedom of the connector to be performedindependently of one another.

The ability to rotate the first and second bodies 610, 680 relative toone another about the rotation axis A1 can advantageously allow firstand second rods R1, R2 to be locked together even when the rods areobliquely angled with respect to one another, e.g., in the sagittalplane or in the coronal plane. The connector 600 can be particularlyuseful in connecting tandem rods of a spinal fixation construct acrossthe cervical-thoracic (CT) junction of a patient. For example, theconnector 600 can secure the rods R1, R2 in a laterally-offsetarrangement to accommodate the different screw trajectories that mayoccur at the CT junction. By way of further example, the ability of theconnector 600 to articulate can allow a cervical rod and a thoracic rodto be locked to one another at an oblique angle in the sagittal plane,e.g., to restore natural lordosis or kyphosis. The connector 600 canalso be particularly useful in spinal deformity correction and otherprocedures in which multiple angled rods are to be coupled to oneanother.

FIGS. 7A-7O illustrate an exemplary embodiment of a connector 700. Asshown, the connector 700 can include a first body 710 that defines afirst rod-receiving recess or channel 712 and a second body 780 thatdefines a second rod-receiving recess or channel 782. The first andsecond bodies 710, 780 can be connected to one another at least in partby a hinge pin 714 that defines a rotation axis A1 about which thebodies can rotate relative to one another. In the illustratedembodiment, the hinge pin 714 can project laterally from the first body710 to a free end. The free end of the hinge pin 714 can be receivedwithin an interior cavity 784 formed in the second body 780. Theconnector 700 can include first and second fasteners 720, 722 configuredto secure first and second rods R1, R2 or other fixation elements to theconnector 700 within the respective rod-receiving recesses 712, 782. Thehinge pin 714 of the first body 710 can include a retention slot 718configured to receive a distal projection 752 of a saddle 750 disposedin the second rod-receiving recess 782, thereby preventing disassemblyof the first and second bodies 710, 780.

As discussed further below, the structural integrity of the connector700 can be improved to reduce the risk of the hinge pin 714 breakingunder an applied shear force between the first and second bodies 710,780. For example, as shown in the illustrated embodiment, the structuralintegrity of the hinge pin 714 can be improved by forming the retentionslot 718 in close proximity to the free end of the hinge pin 714, suchthat the slot can be exposed through the second rod-receiving recess 782while providing the hinge pin with a maximum cross sectional area for asignificant portion of its length. Alternatively or in addition, in someembodiments, the locking strength of the connector 700 can be increasedby maximizing the contact surface area between the saddle 750 and thehinge pin 714. Alternatively or in addition, in some embodiments, thefree end of the hinge pin 714 can be configured to interact with athrough hole opening 798 defined in the second body 780 to limit thedegree of rotation by the pin, and thereby limit the relative rotationpermitted between the bodies 710, 780.

The first body 710 of the connector 700, including the hinge pin 714, isshown in greater detail in FIGS. 7C through 7E. The first body 710 caninclude proximal and distal ends 710 p, 710 d that define aproximal-distal axis A2. The proximal end 710 p of the body 710 caninclude a pair of spaced apart arms 724, 726 that extend from the distalportion 710 d of the body 710 to a free end. The spaced apart arms 724,726 can define the first rod-receiving recess 712 therebetween. Thefirst rod-receiving recess 712 can be open in a proximal direction, suchthat a rod R1 can be inserted into the recess by moving the rod distallywith respect to the connector 700. Alternatively, the firstrod-receiving recess 712 can be open in distal direction, open in alateral direction, or closed such that the rod R1 must be translatedalong the axis A3 to insert the rod into the recess 712.

The hinge pin 714 can project along the rotation axis A1 from an outersurface 728 of the arm 726. As shown in the illustrated embodiment, theouter surface 728 of the arm 726 can extend vertically from the distalend 710 d of the first body 710. The hinge pin 714 can extendperpendicular from a distal end portion of the outer surface 728 of thearm 726. The hinge pin 714 can include opposed first and second endsthat define a central longitudinal axis A6 extending therebetween. Thelongitudinal axis A6 can be collinear with the rotation axis A1 of theconnector 700. The hinge pin 714 can be formed integrally ormonolithically with the first body 710 as shown, or can be fixedlyattached thereto, e.g., by welding or other processes.

The hinge pin 714 can have a first portion 730, a second portion 732 andan intermediate portion or rib 734 that connects the first and secondportions. The first portion 730 of the hinge pin 714 can have acylindrical or other suitable shape that allows the pin to freely rotatewithin the cavity 784 of the second body 780. The second portion 732 ofthe hinge pin 714 can have a semi-cylindrical or other suitable shapehaving a cross section that can interact with the second body 780 tolimit rotation of the pin within the cavity 784. In some embodiments,the second portion 732 of the pin 714 can have a semi-circular orD-shaped cross section. The rib 734 of the hinge pin 714 can have acylindrical or other suitable shape to form the retention slot 718between the first portion 730 and the second portion 732 of the pin. Thelength of the slot 718 can be defined by the length of the rib 734disposed between a sidewall 740 of the first portion 730 and an opposingsidewall 742 of the second portion 732. Each of the opposing sidewalls740, 742 can lie in a plane perpendicular to the rotation axis A1. Asdiscussed further below, the slot 718 can be configured to receive adistal projection of a saddle 750 disposed in the second rod-receivingrecess 782, thereby preventing disassembly of the first and secondbodies 710, 780.

The second body 780 is shown in greater detail in FIGS. 7F through 7H.The second body 780 can include proximal and distal ends 780 p, 780 dthat define a proximal-distal axis A4. The proximal end 780 p of thebody 780 can include a pair of spaced apart arms 786, 788 that definethe second rod-receiving recess 782 therebetween. A rod R2 disposed inthe second rod-receiving recess 782 can have a central longitudinal rodaxis A5. The second rod-receiving recess 782 can be open in a proximaldirection, such that a rod R2 can be inserted into the recess by movingthe rod distally with respect to the connector 700. Alternatively, thesecond rod-receiving recess 782 can be open in distal direction, open ina lateral direction, or closed such that the rod R2 must be translatedalong the axis A5 to insert the rod into the recess 782. Each of thearms 786, 788 can include recesses or grooves 790 for retaining thesaddle 750 within the body 780. The second body 780 can include an outersurface 792 that opposes the outer surface 728 of the first body 710.

The distal end 780 d of the second body 780 can define an interiorcavity 784 in which a free end of the hinge pin 714 can be received. Asshown in the illustrated embodiment, the cavity 784 be a through holethat extends from a first opening 794 formed in the outer surface 792 toa second opening 798 formed in the opposite outer surface 796 of thesecond body 780. As discussed further below, the second opening 798formed in the outer surface 796 of the second body 780 can be configuredto at least partially receive and interact with the free end portion 732of the hinge pin 714 and thereby limit rotation of the pin within thecavity 784. As shown in FIG. 7H, the second opening in the outer surface796 of the second body can have a semi-circular or D-shaped crosssection. At least one dimension of the cavity 784 can be greater than acorresponding dimension of the hinge pin 714 to allow the hinge pin totranslate within the cavity along the rotation axis A1.

The saddle 750 is shown in greater detail in FIGS. 7I through 7K. Thesaddle 750 can be generally cylindrical with first and second arms 754,756 extending in a proximal direction to respective free ends of thearms. The first and second arms 754, 756 of the saddle 750 can define arod seat 758 therebetween. The first and second arms 754, 756 of thesaddle 750 can include projections 760 (e.g., spring tabs) extendingradially outward therefrom. The radial projections 760 can be configuredto snap into or otherwise be received within grooves or other recesses790 of the second body 780 to retain the saddle 750 therein.

The saddle 750 can have a recessed distal-facing bearing surface 762 anda saddle projection 752 extending therefrom. The recessed distal-facingbearing surface 762 can have a planar, ramped, curved or other suitablecontour configured to contact and bear against an exterior surface ofthe hinge pin 714. As shown in the illustrated embodiment, the recessedbearing surface 762 of the saddle 750 can be curved to contact and bearagainst the cylindrical-shaped surface of the first portion 730 of thehinge pin 714. The saddle projection 752 can extend distally from thedistal-facing bearing surface 762 to maintain coupling of the first andsecond bodies 710, 780.

As shown in the FIGS. 7J and 7K, the distal saddle projection 752 can bealigned with an arm 756 of the saddle 750. For example, as shown in theillustrated embodiment, the distal saddle projection 752 can extenddistally along an edge of the saddle 750 coplanar with the saddle arm756. In some embodiments, the distal saddle projection 752 can extenddistally from the recessed bearing surface 762 of the saddle, such thatthe projection is disposed adjacent to the edge of the saddle 750 in aplane parallel to the saddle arm 756.

As discussed further below, by disposing the distal saddle projection752 at the edge or adjacent to the edge of the saddle 750, the contactsurface area can be maximized between the first portion 730 of the hingepin 714 and the distal-facing bearing surface 762 of the saddle 750.Maximizing the contact surface area between the hinge pin 714 and thesaddle 750 can increase the locking strength of the connector 700 toresist rotation between the first and second bodies 710, 780. In someembodiments, the saddle projection 752 can define a recess 754 sized topartially receive the intermediate portion (or rib) 734 of the hinge pin714 and thereby allow the rib to rotate within the recess.

As shown in FIG. 7L through 7O, the connector 700 can be assembled byinserting the hinge pin 714 through the first opening 794 of the outersurface 792 of the second body 780 and into the cavity 784 until thefree end portion 732 of the pin is received in the second opening 798 ofthe outer surface 796. When the free end portion 732 of the hinge pin714 is received in the second opening 798 of the second body 780, theretention slot 718 of the pin can be exposed proximally through thesecond rod-receiving recess 782, such that the slot is aligned with theedge of the recess 782 closest to the arm 788 of the second body 780. Insome embodiments, the slot 718 can be offset from the edge of the secondrod-receiving recess 782 between the central longitudinal rod axis A5and the arm 788 of the second body 780.

By forming the retention slot 718 in close proximity to the free end ofthe hinge pin 714, e.g., such that the slot is exposed at or adjacent tothe edge of the second rod-receiving recess 782, the hinge pin can havea maximum cross sectional area for a significant portion of its length,and thereby improve the structural integrity of the connector 700. Forexample, in some embodiments, the first portion 730 of the hinge pin 714can have a maximum cross sectional area that extends longitudinally fromthe outer bearing surface 728 of the first body 710 to more than halfwayacross the width of the second rod-receiving recess 782. In suchembodiments, the risk of the hinge pin 714 breaking under an appliedshear force between the first and second bodies 710, 780 can be reduced.

As shown in FIG. 7M, the saddle 750 can be inserted into the proximalend 780 p of the second body 780 and distally advanced until the distalsaddle projection 752 is received in the slot 718 of the hinge pin 714.The radial projections 760 of the saddle arms 754, 756 can snap into thegrooves or recesses 790 of the second body 780 to retain the saddle 750.When disposed in the second body 780, the first and second arms 754, 756of the saddle 750 can be aligned with the first and second arms 786, 788of the second body such that rod seat 758 is aligned with the secondrod-receiving recess 782. Accordingly, the second rod R2 can besimultaneously cradled between the arms 754, 756 of the saddle 750 andthe arms 786, 788 of the second body 780 when the rod R2 is disposed inthe second rod-receiving recess 782.

At this stage of assembly, even before locking rods within the connector700, the saddle 750 can interfere with the slot 718 of the hinge pin 714to prevent the pin from being removed from the second body 780. Forexample, when the saddle projection 752 is received in the slot 718, thelateral-facing surfaces of the projection can bear against the opposingsidewalls 740, 742 of the slot to prevent removal of the pin, andthereby maintain coupling of the first and second bodies 710, 780. Thedepth of the slot 718 can be configured to be greater than the height ofthe distal saddle projection 752 to ensure that the distal-facingsurface 762 of the saddle bears against the first portion 730 of the pinduring locking.

A first rod R1 can be seated in the first rod receiving recess 712 ofthe first body 710 and secured to the connector 700 by tightening thefirst fastener 720. The first fastener 720 can include an exteriorthread configured to mate with the interior threads formed on the arms724, 726 of the first body 710 to allow the first fastener to beadvanced or retracted along the axis A2 with respect to the body byrotating the first fastener about the axis A2. The distal surface of thefirst fastener 720 can be configured to contact and bear against a rodR1 disposed in the first rod-receiving recess 712 to lock the rod to theconnector 700. When tightened against the rod R1, the first fastener 720can prevent the rod from translating relative to the connector 700 alongthe axis A3 and/or from rotating with respect to the connector about theaxis A3. The first rod R1 can be seated in the first rod-receivingrecess 712, while the second body 780 can remain free to rotate relativeto the first body 710 about the rotation axis A1 even after the firstrod R1 is locked to the connector 700.

A second rod R2 can be seated in the rod seat 758 of the saddle 750disposed in the second rod receiving recess 782 of the second body 780.The second rod R2 can be secured to the connector 700 by tightening thesecond fastener 722. The second fastener 722 can include an exteriorthread configured to mate with the interior threads formed on the arms786, 788 of the second body 780 to allow the second fastener to beadvanced or retracted along the axis A4 with respect to the body byrotating the second fastener about the axis A4. The second fastener 722can include a driving interface configured to receive a driver forapplying a rotational force to the second fastener 722 about the axisA4.

The distal surface of the second fastener 722 can be configured tocontact and bear against the rod R2 disposed in the saddle 750 to lockthe rod to the connector 700. When tightened against the rod R2, thesecond fastener 722 can prevent the rod from translating relative to theconnector 700 along the axis A5 and/or from rotating with respect to theconnector about the axis A5. While a unitary set screw 722 is shown, itwill be appreciated that other fasteners can be used, instead or inaddition, such as a closure cap that advances and locks by quarter-turnrotation, a closure cap that slides in laterally without rotating, a nutthat threads onto an exterior of the body, or a dual-component set screwwith independently-rotatable inner and outer members, the inner memberacting on the rod R2 and the outer member acting on proximal free endsof the saddle arms 754, 756.

Before fully tightening one or both fasteners 720, 722, the bodies 710,780 can be rotated relative to one another about the axis A1 as desiredby the user. The degree of rotation of the hinge pin 714, and therebythe relative rotation permitted between the bodies 710, 780, can belimited by the interaction between the free end portion 732 of the hingepin 714 and the opening 798 in the outer surface 796 of the second body780.

As shown in FIG. 7N, the through hole opening 798 in the outer surface796 of the second body 780 and the free end portion 732 of the hinge pin714 can be configured to have respective cross sectional profiles,perpendicular to the rotation axis A1, that allow the pin to rotateclockwise and counter-clockwise between a predetermined range of anglesabout the rotation axis A1. For example, in the illustrated embodiment,the free end portion 732 of the pin and the through hole opening 798 ofthe second body 780 can both have semi-circular or D-shaped crosssectional profiles. As shown, the semi-circular profile of the throughhole opening 798 is larger than the semi-circular profile of the freeend portion 732 of the pin to allow the free end portion of the pin torotate about the rotation axis A1 within the through hole opening of thesecond body. When the hinge pin 714 rotates clockwise or counterclockwise about the rotation axis A1, the extent of such rotation can berestricted by bearing surfaces 735, 737 of the free end portion 732contacting an inner wall of through hole opening 798. In someembodiments, the interaction between the through hole opening 798 andthe free end portion 732 of the hinge pin 714 can limit the range ofrotation of the pin symmetrically with respect to the rotation axis A1.For example, in some embodiments, the range of rotation of the hinge pin714 can be limited to ±30 degrees, ±60 degrees, ±180 degrees, or othersymmetrical range suitable depending on the surgical procedure. In someembodiments, the interaction between the through hole opening 798 andthe free end portion 732 of the hinge pin 714 can limit the range ofrotation of the pin asymmetrically with respect to the rotation axis A1.

Once the first and second bodies 710, 780 are rotated to the desiredorientation, the second fastener 722 can then be tightened to lock therelative rotation of the first and second bodies 710, 780. As the secondfastener 722 is tightened, the second rod R2 can be urged distallyagainst the saddle 750, thereby causing the saddle to urge distallyagainst the hinge pin 714. For example, as shown in the illustratedembodiment of FIG. 7O, the distal-facing bearing surface 762 of thesaddle 750 can urged to contact and bear against the counter bearingsurface of the first portion 730 of the hinge pin 714. By forming theslot 718 as close as possible to the free end portion 732 of the pin,the contact surface area between the distal-facing bearing surface 762of the saddle 750 and the counter bearing surface of the hinge pin 714can be maximized. For example, in some embodiments, the contact surfacearea between the saddle 750 and the hinge pin 714 can extend in thedirection of the longitudinal axis A6 for a continuous length that isgreater than half the width of the second rod-receiving recess 782. Insome embodiments, the contact surface area between the saddle 750 andthe pin 714 can extend for a continuous length between 70% and 90% ofthe width of the second rod-receiving recess 782. By maximizing thecontact surface area between the saddle 750 and the pin 714, the lockingforce and thus the locking strength of the connector 700 can beincreased to resist relative rotation of the first and second bodies710, 780.

In other arrangements, the second fastener 722 can bear directly againstthe saddle 750. For example, the second fastener 722 can include anouter set screw that bears against the saddle arms 754, 756 to lockrelative rotation of the bodies 710, 780, and an inner set screw thatbears against the second rod R2 to secure the second rod to theconnector 700.

It will be appreciated that the connector 700 can allow locking of thefirst rod R1 to the connector and locking of the rotationaldegree-of-freedom of the connector to be performed independently of oneanother.

In some embodiments, the connector 700 can include various features of aunilateral locking interface, including but not limited to one or moregrooves 702 and surface projections 704. The unilateral lockinginterface enables a surgical instrument that includes a unilaterallocking mechanism (not shown) to rigidly hold onto one side of theconnector 700. Exemplary unilateral locking interfaces that can beincluded in the connector 700 are disclosed in U.S. patent applicationSer. No. 15/843,618, filed on Dec. 15, 2017 and entitled “UnilateralImplant Holders and Related Methods” (now published asUS-2019-0183541-A1), the entire contents of which are herebyincorporated by reference.

The connector 700 can include any combination of the features of theconnector 500 described above. For example, as discussed above withrespect to FIGS. 5A-5O, the exterior surface of the hinge pin 714 caninclude sharp corners or other surface features (now shown) that canbear against the inner wall of the cavity 784 of the second body 780 toincrease the locking strength of the connector 700.

The ability to rotate the first and second bodies 710, 780 relative toone another about the rotation axis A1 can advantageously allow firstand second rods R1, R2 to be locked together even when the rods areobliquely angled with respect to one another, e.g., in the sagittalplane or in the coronal plane. The connector 500 can be particularlyuseful in connecting tandem rods of a spinal fixation construct acrossthe cervical-thoracic (CT) junction of a patient. For example, theconnector 500 can secure the rods R1, R2 in a laterally-offsetarrangement to accommodate the different screw trajectories that mayoccur at the CT junction. By way of further example, the ability of theconnector 500 to articulate can allow a cervical rod and a thoracic rodto be locked to one another at an oblique angle in the sagittal plane,e.g., to restore natural lordosis or kyphosis. The connector 500 canalso be particularly useful in spinal deformity correction and otherprocedures in which multiple angled rods are to be coupled to oneanother.

Any of the connectors 100, 200, 300, 400, 500, 600, and 700 describedabove can include a taper-lock mating between the first and secondbodies. The taper lock can be formed by a conical male feature wedgedinto a conical female feature. The cone angle of the male feature can bein the range of about 5 degrees to about 35 degrees. The cone angle ofthe male feature can be about 20 degrees. The cone angle of the femalefeature can be in the range of about 5 degrees to about 35 degrees. Thecone angle of the female feature can be about 20 degrees. The male andfemale cone features can have the same cone angle or different coneangles. The connector geometry can be selected such that there is aspace between the first and second bodies along the axis A1 when theconnector is fully tightened, which can ensure that the taper lock bearsmost or all of the locking force. The male and female features can beflat cones, or can include surface features such as axial splines.

The degree to which the first and second bodies can rotate relative toone another can vary in any of the connectors 100, 200, 300, 400, 500,600, and 700 described above. The first body can be rotatable up to 360degrees with respect to the second body. The first body can be rotatableup to about 180 degrees with respect to the second body. The first bodycan be rotatable up to about 60 degrees with respect to the second body.

The geometries of the rod-receiving recesses of any of the connectors100, 200, 300, 400, 500, 600, and 700 described above can vary. One orboth recesses can include a V-shaped seat configured to accommodate rodsof different diameters.

An exemplary method of using the connectors disclosed herein isdescribed below.

The procedure can begin by forming an open or percutaneous incision inthe patient to access a target site. The target site can be one or morevertebrae, a long bone or multiple portions of a long bone, or any otherbone or non-bone structure of the patient. As shown in FIG. 8 , thetarget site can be multiple vertebrae in the patient's cervical andthoracic spine.

Bone anchors can be driven into one or more of the vertebrae and spinalrods can be attached thereto using known techniques. In the illustratedexample, bilateral spinal rods R1, R2 are coupled to four adjacentvertebrae V1-V4 using eight bone anchors S1-S8. In addition, bilateralrods R3, R4 are coupled to two additional vertebrae V5-V6 using fourbone anchors S9-S12. The rods R1, R2 can be connected to the rods R3,R4, respectively, using two connectors C1-C2 of the type describedherein (e.g., any of the connectors 100, 200, 300, 400, 500, 600, 700 orcombinations or variations thereof).

The connectors C1-C2 can be articulated and locked in an articulatedposition as shown. This can allow the principal longitudinal axes of therods R1, R3 to be obliquely angled with respect to each other, and/orfor the principal longitudinal axes of the rods R2, R4 to be obliquelyangled with respect to each other.

All of the rods R1-R4, the connectors C1-C2, and the bone anchors S1-S12can be installed in a single procedure.

Alternatively, the rods R1, R2 and the bone anchors S1-S8 may have beeninstalled in a previous procedure, and the current procedure can be arevision procedure in which the rods R3, R4, the connectors C1-C2, andthe bone anchors S9-S12 are installed to extend the previously-installedconstruct to additional levels.

The connectors C1-C2 can be attached to position the rods R1-R4 suchthat they overlap in a lateral view. One or both connectors C1-C2 canalso be rotated 90 degrees from the orientation shown to position one orboth rod pairs R1, R3 and R2, R4 such that they overlap in a posterioror anterior view.

The above steps can be repeated to install additional rods and/orconnectors at the same or at different vertebral levels. Finaltightening or other adjustment of the construct can be performed and theprocedure can be completed using known techniques and the incisionclosed.

It should be noted that any ordering of method steps expressed orimplied in the description above or in the accompanying drawings is notto be construed as limiting the disclosed methods to performing thesteps in that order. Rather, the various steps of each of the methodsdisclosed herein can be performed in any of a variety of sequences. Inaddition, as the described methods are merely exemplary embodiments,various other methods that include additional steps or include fewersteps are also within the scope of the present disclosure.

While the methods illustrated and described herein generally involveattaching spinal rods to multiple vertebrae, it will be appreciated thatthe connectors and methods herein can be used with various other typesof fixation or stabilization hardware, in any bone, in non-bone tissue,or in non-living or non-tissue objects. The connectors disclosed hereincan be fully implanted, or can be used as part of an external fixationor stabilization system. The devices and methods disclosed herein can beused in minimally-invasive surgery and/or open surgery.

The devices disclosed herein and the various component parts thereof canbe constructed from any of a variety of known materials. Exemplarymaterials include those which are suitable for use in surgicalapplications, including metals such as stainless steel, titanium, oralloys thereof, polymers such as PEEK, ceramics, carbon fiber, and soforth. The various components of the devices disclosed herein can berigid or flexible. One or more components or portions of the device canbe formed from a radiopaque material to facilitate visualization underfluoroscopy and other imaging techniques, or from a radiolucent materialso as not to interfere with visualization of other structures. Exemplaryradiolucent materials include carbon fiber and high-strength polymers.

Although specific embodiments are described above, it should beunderstood that numerous changes may be made within the spirit and scopeof the concepts described.

The invention claimed is:
 1. A surgical method, comprising: inserting ahinge pin that extends laterally from a first body of a connector to afree end into a cavity formed in a second body of the connector therebycoupling the first body of the connector to the second body of theconnector, the second body having a saddle disposed within arod-receiving recess of the second body, the saddle forming a rod seatfor receiving a spinal fixation element; and orienting the first bodyrelative to the second body such that a slot formed in the hinge pinreceives a saddle protrusion extending distally from the saddle suchthat the saddle prevents removal of the hinge pin from the secondconnector body and a feature formed on the hinge pin restricts rotationof the first body relative to the second body about a rotation axisdefined by a longitudinal axis of the hinge pin to a predetermined rangeof angles.
 2. The surgical method of claim 1, wherein the slot of thehinge pin has an angled cam surface and the saddle protrusion has acorresponding angled bearing surface.
 3. The surgical method of claim 2,further comprising moving a fastener with respect to the second body tosecure a spinal fixation element within the rod receiving recess of thesecond body and thereby lock relative rotation of the first and secondbodies about the rotation axis; wherein moving the fastener with respectto the second body wedges the angled bearing surface of the saddleprotrusion into the angled cam surface of the slot.
 4. The surgicalmethod of claim 1, wherein orienting the first body relative to thesecond body further comprises rotating the first body relative to thesecond body about the rotation axis defined by the longitudinal axis ofthe hinge pin.
 5. The surgical method of claim 4, wherein moving afastener with respect to the second body urges a bearing surface of thesaddle against a corresponding bearing surface of the hinge pin andthereby causes one or more corners of the hinge pin to apply a forceagainst the cavity of the second body.
 6. The surgical method of claim4, wherein rotating the first body relative to the second body about therotation axis defined by the longitudinal axis of the hinge pincomprises rotating the first body with respect to the second body suchthat the saddle protrusion limits a rotation of the hinge pin when aterminal end of the slot of the hinge pin engages and bears against thesaddle protrusion.
 7. The surgical method of claim 4, wherein rotatingthe first body relative to the second body about the rotation axisdefined by the longitudinal axis of the hinge pin comprises rotating thefirst body such that the free end of the hinge pin rotates within anopening defined in the second body of the connector, the opening havinga cross sectional shape that limits rotation of the free end of thehinge pin.
 8. The surgical method of claim 4, wherein rotating the firstbody relative to the second body about the rotation axis defined by thelongitudinal axis of the hinge pin comprises rotating the first bodysuch that the slot of the hinge pin rotates about the saddle protrusionthat extends distally from an edge of the saddle and is aligned with anedge of the rod-receiving recess in the second body.
 9. The surgicalmethod of claim 8, further comprising moving a fastener with respect tothe second body to secure a spinal fixation element within the rodreceiving recess of the second body and thereby lock relative rotationof the first and second bodies about the rotation axis; wherein movingthe fastener with respect to the second body urges a bearing surface ofthe saddle against a corresponding bearing surface of the hinge pin fora continuous length that is greater than half the width of the secondrod-receiving recess.
 10. The surgical method of claim 4, wherein thefeature of the hinge pin is a sidewall of the slot and rotating thefirst body relative to the second body is limited by the saddleprojection contacting the sidewall of the slot.
 11. The surgical methodof claim 4, wherein the feature of the hinge pin is a cross sectionalshape of the free end of the hinge pin and rotating the first bodyrelative to the second body is limited by the cross sectional shape ofthe free end of the hinge pin.
 12. The surgical method of claim 1,further comprising moving a fastener with respect to the second body tosecure a spinal fixation element within the rod receiving recess of thesecond body and thereby lock relative rotation of the first and secondbodies about the rotation axis defined by the longitudinal axis of thehinge pin.
 13. The surgical method of claim 12, wherein the featureformed on the hinge pin is a plurality of planar surfaces that intersectto form one or more corners and the cavity of the second body is formedof a curved inner wall; and wherein the one or more corners of the hingepin apply a force against the cavity of the second body that locks thehinge pin in place when the fastener secures the spinal fixation elementwithin the rod receiving recess of the second body.
 14. The surgicalmethod of claim 13, wherein the force applied by the one or more cornersof the hinge pin is transferred from a force applied by the fastenerthrough the saddle.
 15. The surgical method of claim 1, wherein abearing surface of the saddle adjacent to the saddle protrusion engagesand bears against a corresponding bearing surface of the hinge pinadjacent to the slot.
 16. The surgical method of claim 1, whereinrotation between the first body and second body is limited symmetricallyabout the rotation axis.
 17. The surgical method of claim 1, whereinrotation between the first body and the second body is limitedasymmetrically about the rotation axis.
 18. The surgical method of claim1, wherein the saddle is unitary.
 19. The surgical method of claim 18,wherein the saddle protrusion extends distally along an edge of thesaddle coplanar with an arm of the saddle.
 20. The surgical method ofclaim 1, further comprising moving a fastener with respect to the secondbody to urge the first and second bodies towards one another along therotation axis and thereby lock relative rotation of the first and secondbodies about the rotation axis.
 21. A surgical method, comprising:inserting a hinge pin that extends laterally from a first body of aconnector to a free end into a cavity formed in a second body of theconnector thereby coupling the first body of the connector to the secondbody of the connector, the second body having a unitary saddle disposedwithin a rod-receiving recess of the second body, the saddle forming arod seat for receiving a spinal fixation element; and orienting thefirst body relative to the second body such that a slot formed in thehinge pin receives a saddle protrusion extending distally from thesaddle such that the saddle prevents removal of the hinge pin from thesecond connector body and a feature formed on the hinge pin restrictsrotation of the first body relative to the second body about a rotationaxis defined by the hinge pin to a predetermined range of angles.
 22. Asurgical method, comprising: inserting a hinge pin that extendslaterally from a first body of a connector to a free end into a cavityformed in a second body of the connector thereby coupling the first bodyof the connector to the second body of the connector, the second bodyhaving a saddle disposed within a rod-receiving recess of the secondbody, the saddle forming a rod seat for receiving a spinal fixationelement; orienting the first body relative to the second body such thata slot formed in the hinge pin receives a saddle protrusion extendingdistally from the saddle such that the saddle prevents removal of thehinge pin from the second connector body and a feature formed on thehinge pin restricts rotation of the first body relative to the secondbody about a rotation axis defined by the hinge pin to a predeterminedrange of angles; and moving a fastener with respect to the second bodyto urge the first and second bodies towards one another along therotation axis and thereby lock relative rotation of the first and secondbodies about the rotation axis.